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Sample records for kangaroo rats nonlinear

  1. Monitoring the Stephen's kangaroo rat: An analysis of monitoring methods and recommendations for future monitoring

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document covers a series of analyses to explore and summarize previous monitoring efforts of Stephens Kangaroo Rats (SKR) and make recommendations for future...

  2. Positive interactions between desert granivores: localized facilitation of harvester ants by kangaroo rats.

    Directory of Open Access Journals (Sweden)

    Andrew J Edelman

    Full Text Available Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis mounds and rough harvester ant (Pogonomyrmex rugosus colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (<10 m. Mortality risk of vulnerable, recently founded harvester ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species.

  3. Positive interactions between desert granivores: localized facilitation of harvester ants by kangaroo rats.

    Science.gov (United States)

    Edelman, Andrew J

    2012-01-01

    Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis) mounds and rough harvester ant (Pogonomyrmex rugosus) colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species.

  4. Botfly (Diptera:Oestridae) parasitism of Ord's kangaroo rats (Dipodomys ordii) at Suffield National Wildlife Area, Alberta, Canada.

    Science.gov (United States)

    Gummer, D L; Forbes, M R; Bender, D J; Barclay, R M

    1997-08-01

    During field study of Ord's kangaroo rat (Dipodomys ordii) at Suffield National Wildlife Area, Alberta, Canada, a high prevalence of parasitism by botfly (Diptera: Oestridae) larvae was observed. Botflies have not previously been documented as parasites of kangaroo rats. Botfly parasitism could have a significant impact on the growth, survival, and reproduction of Ord's kangaroo rat, which is considered a vulnerable species in Canada. Therefore, it is important to investigate how botfly parasitism varies with season and with gender or age of host. In 1995, 525 individual kangaroo rats were caught by nightlighting and live trapping for a total of 952 capture records. Upon capture, each kangaroo rat was ear-tagged and thoroughly examined for parasites and wounds. Third-instar botfly (Cuterebra polita) larvae were observed in kangaroo rats between 16 June and 23 August. Prevalence was 34% based on 454 kangaroo rats sampled during that time, whereas the mean intensity was 2.3 larvae per infested host (n = 156, range = 1-11). In contrast to some other studies of botfly parasitism of rodents, there were no gender or age biases in either prevalence or intensity of infestation. The index of dispersion was 2.8, indicating that the parasites were aggregated in hosts. Botfly parasitism could be an important factor affecting northern populations of kangaroo rats; future investigations into the potential effects of botfly larvae on host fitness are warranted.

  5. Draft De Novo Transcriptome of the Rat Kangaroo Potorous tridactylus as a Tool for Cell Biology.

    Science.gov (United States)

    Udy, Dylan B; Voorhies, Mark; Chan, Patricia P; Lowe, Todd M; Dumont, Sophie

    2015-01-01

    The rat kangaroo (long-nosed potoroo, Potorous tridactylus) is a marsupial native to Australia. Cultured rat kangaroo kidney epithelial cells (PtK) are commonly used to study cell biological processes. These mammalian cells are large, adherent, and flat, and contain large and few chromosomes-and are thus ideal for imaging intra-cellular dynamics such as those of mitosis. Despite this, neither the rat kangaroo genome nor transcriptome have been sequenced, creating a challenge for probing the molecular basis of these cellular dynamics. Here, we present the sequencing, assembly and annotation of the draft rat kangaroo de novo transcriptome. We sequenced 679 million reads that mapped to 347,323 Trinity transcripts and 20,079 Unigenes. We present statistics emerging from transcriptome-wide analyses, and analyses suggesting that the transcriptome covers full-length sequences of most genes, many with multiple isoforms. We also validate our findings with a proof-of-concept gene knockdown experiment. We expect that this high quality transcriptome will make rat kangaroo cells a more tractable system for linking molecular-scale function and cellular-scale dynamics.

  6. Derivation of soil screening thresholds to protect chisel-toothed kangaroo rat from uranium mine waste in northern Arizona

    Science.gov (United States)

    Hinck, Jo E.; Linder, Greg L.; Otton, James K.; Finger, Susan E.; Little, Edward E.; Tillitt, Donald E.

    2013-01-01

    Chemical data from soil and weathered waste material samples collected from five uranium mines north of the Grand Canyon (three reclaimed, one mined but not reclaimed, and one never mined) were used in a screening-level risk analysis for the Arizona chisel-toothed kangaroo rat (Dipodomys microps leucotis); risks from radiation exposure were not evaluated. Dietary toxicity reference values were used to estimate soil-screening thresholds presenting risk to kangaroo rats. Sensitivity analyses indicated that body weight critically affected outcomes of exposed-dose calculations; juvenile kangaroo rats were more sensitive to the inorganic constituent toxicities than adult kangaroo rats. Species-specific soil-screening thresholds were derived for arsenic (137 mg/kg), cadmium (16 mg/kg), copper (1,461 mg/kg), lead (1,143 mg/kg), nickel (771 mg/kg), thallium (1.3 mg/kg), uranium (1,513 mg/kg), and zinc (731 mg/kg) using toxicity reference values that incorporate expected chronic field exposures. Inorganic contaminants in soils within and near the mine areas generally posed minimal risk to kangaroo rats. Most exceedances of soil thresholds were for arsenic and thallium and were associated with weathered mine wastes.

  7. Ord's kangaroo rats living in floodplain habitats: Factors contributing to habitat attraction

    Science.gov (United States)

    Miller, M.S.; Wilson, K.R.; Andersen, D.C.

    2003-01-01

    High densities of an aridland granivore, Ord's kangaroo rat (Dipodomys ordii), have been documented in floodplain habitats along the Yampa River in northwestern Colorado. Despite a high probability of inundation and attendant high mortality during the spring flood period, the habitat is consistently recolonized. To understand factors that potentially make riparian habitats attractive to D. ordii, we compared density and spatial pattern of seeds, density of a competitor (western harvester ant, Pogonomyrmex occidentalis), and digging energetics within floodplain habitats and between floodplain and adjacent upland habitats. Seed density within the floodplain was greatest in the topographically high (rarely flooded) floodplain and lowest immediately after a spring flood in the topographically low (frequently flooded) floodplain. Seed densities in adjacent upland habitat that never floods were higher than the lowest floodplain habitat. In the low floodplain prior to flooding, seeds had a clumped spatial pattern, which D. ordii is adept at exploiting; after spring flooding, a more random pattern resulted. Populations of the western harvester ant were low in the floodplain relative to the upland. Digging by D. ordii was energetically less expensive in floodplain areas than in upland areas. Despite the potential for mortality due to annual spring flooding, the combination of less competition from harvester ants and lower energetic costs of digging might promote the use of floodplain habitat by D. ordii.

  8. (Kangaroo grass) at various growth stages

    African Journals Online (AJOL)

    STORAGESEVER

    2009-04-06

    Apr 6, 2009 ... Key words: Kangaroo grass, biomass, dry matter, rangeland, growth stages. INTRODUCTION ... Soil organic matter, soil porosity and nutrient ... as soil moisture approaches field capacity (Nolan, 1994). Because Kangaroo ...

  9. About Skin-to-Skin Care (Kangaroo Care)

    Science.gov (United States)

    ... Size Email Print Share About Skin-to-Skin Care Page Content Article Body You may be able ... care, also called kangaroo care. What is Kangaroo Care? Kangaroo care was developed in South America as ...

  10. Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?

    Science.gov (United States)

    Janis, Christine M; Buttrill, Karalyn; Figueirido, Borja

    2014-01-01

    Sthenurine kangaroos (Marsupialia, Diprotodontia, Macropodoidea) were an extinct subfamily within the family Macropodidae (kangaroos and rat-kangaroos). These "short-faced browsers" first appeared in the middle Miocene, and radiated in the Plio-Pleistocene into a diversity of mostly large-bodied forms, more robust than extant forms in their build. The largest (Procoptodon goliah) had an estimated body mass of 240 kg, almost three times the size of the largest living kangaroos, and there is speculation whether a kangaroo of this size would be biomechanically capable of hopping locomotion. Previously described aspects of sthenurine anatomy (specialized forelimbs, rigid lumbar spine) would limit their ability to perform the characteristic kangaroo pentapedal walking (using the tail as a fifth limb), an essential gait at slower speeds as slow hopping is energetically unfeasible. Analysis of limb bone measurements of sthenurines in comparison with extant macropodoids shows a number of anatomical differences, especially in the large species. The scaling of long bone robusticity indicates that sthenurines are following the "normal" allometric trend for macropodoids, while the large extant kangaroos are relatively gracile. Other morphological differences are indicative of adaptations for a novel type of locomotor behavior in sthenurines: they lacked many specialized features for rapid hopping, and they also had anatomy indicative of supporting their body with an upright trunk (e.g., dorsally tipped ischiae), and of supporting their weight on one leg at a time (e.g., larger hips and knees, stabilized ankle joint). We propose that sthenurines adopted a bipedal striding gait (a gait occasionally observed in extant tree-kangaroos): in the smaller and earlier forms, this gait may have been employed as an alternative to pentapedal locomotion at slower speeds, while in the larger Pleistocene forms this gait may have enabled them to evolve to body sizes where hopping was no longer

  11. How Does a Hopping Kangaroo Breathe?

    Science.gov (United States)

    Giuliodori, Mauricio J.; Lujan, Heidi L.; Janbaih, Hussein; DiCarlo, Stephen E.

    2010-01-01

    We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the…

  12. Parents\\' lived experience of providing kangaroo care to their ...

    African Journals Online (AJOL)

    Parents\\' lived experience of providing kangaroo care to their preterm infants. ... While there is good evidence to demonstrate the benefits of kangaroo care in low ... experience of birth; anxiety and barriers; an intimate connection; adjustments, ...

  13. HYPOALDOSTERONISM IN A MATSCHIE'S TREE KANGAROO (DENDROLAGUS MATSCHIEI).

    Science.gov (United States)

    Whoriskey, Sophie T; Bartlett, Susan L; Baitchman, Eric

    2016-06-01

    A 20-yr-old female Matschie's tree kangaroo (Dendrolagus matschiei) was diagnosed with hypoaldosteronism, a rare condition in which the body fails to produce normal amounts of the mineralocorticoid aldosterone. Aldosterone plays a key role in body salt homeostasis, increasing sodium reabsorption and promoting excretion of potassium. Hypoaldosteronism resulted in decreased appetite, lethargy, and weight loss in conjunction with hyponatremia, hyperkalemia, and hypercalcemia in this tree kangaroo. The animal was successfully managed with mineralocorticoid replacement using desoxycorticosterone pivalate. To the authors' knowledge this is the first report of hypoaldosteronism in a tree kangaroo and one of the few reports in the veterinary literature in any species.

  14. Setting up Kangaroo Mother Care at Queen Elizabeth Central ...

    African Journals Online (AJOL)

    Central Hospital, Blantyre - A practical approach .... It is not sustainable .... This is a very distressing event for the mother, other mothers and .... management of well preterm infants: a pilot study. ... Kangaroo Mother Care — A practical guide.

  15. Mothers’ Experiences with Premature Neonates about Kangaroo Care: Qualitative Approaches

    Directory of Open Access Journals (Sweden)

    Tahere Salimi

    2014-01-01

    Full Text Available Introduction:  Premature neonates admitted in NICU besides being separated from their mothers are prone to inevitably painful and stressful situations. Kangaroo care is the most effective method to get rid of this separation and its negative consequences. This study was performed to determine the experiences of mothers having premature neonates concerning Kangaroo care.   Material and Methods: The present study is a qualitative research in which focus group discussion method is used for data collection. Research society consisted of mothers having premature neonates Research group reread and categorized the qualitative findings. Contents of interviews were analyzed using the conventional interpretation approach introduced by Dicklman Method.   Results: Through content analysis of information emerged two major categories including mothers’ experiences about advantages of kangaroo care in interaction with neonate, and, feeling of physical-mental healthiness of neonate. Executive obstacles of kangaroo care from mothers’ standpoint were also discussed, which will be subsequently presented.   Discussion: According to the obtained results, it seems vital to highlight kangaroo care as a safe and effective clinical care-taking treatment in nursery of premature neonates in all hospitals. Nurses shall provide all mothers with the needed instructions for holding the premature and lower-weight neonate properly on their chests and shall promote their knowledge level concerning positive effects of kangaroo care including induction of tranquil sleep, optimization of physiological conditions of neonate, and removal of suckling obstacles.

  16. Heart Rate Variability in Nonlinear Rats with Different Orientation and Exploratory Activity in the Open Field.

    Science.gov (United States)

    Kur'yanova, E V; Teplyi, D L; Zhukova, Yu D; Zhukovina, N V

    2015-12-01

    The basic behavioral activity of nonlinear rats was evaluated from the sum of crossed peripheral and central squares and peripheral and central rearing postures in the open fi eld test. This index was low (30 episodes). Male rats with high score of orientation and exploratory activity were characterized by higher indexes of total heart rate variability than rats with low or intermediate activity. Specimens with a greater contribution of VLF waves into the total power spectrum of heart rate variability were shown to dominate among the rats with high behavioral activity. Our results are consistent with the notions of a suprasegmental nature of VLF waves.

  17. Nonlinear system analysis of renal autoregulation in normotensive and hypertensive rats

    DEFF Research Database (Denmark)

    Chon, K H; Chen, Y M; Holstein-Rathlou, N H;

    1998-01-01

    We compared the dynamic characteristics in renal autoregulation of blood flow of normotensive Sprague-Dawley rats (SDR) and spontaneously hypertensive rats (SHR), using both linear and nonlinear systems analysis. Linear analysis yielded only limited information about the differences in dynamics...... of nonlinear interactions between the oscillatory components of the myogenic mechanism and tubuloglomerular feedback (TGF) at the level of whole kidney blood flow in SDR. An interaction between these two mechanisms had previously been revealed for SDR only at the single nephron level. However, nonlinear......, NMSE are significantly higher in SHR than SDR, suggesting a more complex nonlinear system in SHR. The contribution of the third-order kernel in describing the dynamics of renal autoregulation in arterial blood pressure and blood flow was found to be important. Moreover, we have identified the presence...

  18. The role of inspections in the commercial kangaroo industry

    Directory of Open Access Journals (Sweden)

    Keely Boom

    2013-08-01

    Full Text Available This article provides an assessment of the enforcement of the law governing commercial kangaroo killing, focusing particularly upon inspectorial practices. Australia’s kangaroo industry is the largest commercial kill of land-based wildlife in the world. Professional shooters hunt kangaroos in rural and remote locations at night. Due to the remote and decentralised nature of the killing, the industry presents unique challenges to law enforcement agencies that are responsible for the enforcement of animal welfare standards. This article focuses upon the role that inspections have in detecting offences within the commercial kangaroo industry. It provides a comparative analysis across the states, highlighting key differences in terms of inspectorial practices and the resulting outcomes. A common theme across all of the jurisdictions is that none of the agencies responsible for enforcement regularly conduct inspections of shooters, making it impossible to ensure that these parties are complying with the National Code of Practice for the Humane Shooting of Kangaroos and Wallabies. Recommendations for reform are offered, including stronger compliance policy, higher rates of inspection, increased resourcing and the introduction of alternative methods of inspection.

  19. Phylogeny of kangaroo apples (Solanum subg. Archaesolanum, Solanaceae).

    Science.gov (United States)

    Poczai, Péter; Hyvönen, Jaakko; Symon, David E

    2011-11-01

    Kangaroo apples, subgenus Archaesolanum, are a unique and still poorly known group within the genus Solanum. Here we aimed to reveal phylogeny, historical biogeography and age of diversification of Archaesolanum. We sampled all recognized species of the group and sequenced three chloroplast regions, the trnT-trnL spacer, trnL intron and trnL-trnF spacer to calibrate a molecular clock to estimate the age of the group. Distributional data were combined with the results of phylogenetic analysis to track the historical processes responsible for the current range of the group. Our analysis supported the monophyly of the kangaroo apples and the biogeographical disjunction between the two subclades within the group. Based on the divergence time estimates the most recent common ancestor of kangaroo apples is from the late Miocene age (~9 MYA). Based on the age estimate the common ancestors of the kangaroo apples are presumed to have arrived in Australia by long-distance dispersal. The two distinct lineages within the group have separated during the aridification of the continent and further speciated in the brief resurgence of rainforests during the Pliocene.

  20. What is kangaroo mother care? Systematic review of the literature

    Directory of Open Access Journals (Sweden)

    Grace J Chan

    2016-06-01

    Full Text Available Kangaroo mother care (KMC, often defined as skin–to–skin contact between a mother and her newborn, frequent or exclusive breastfeeding, and early discharge from the hospital has been effective in reducing the risk of mortality among preterm and low birth weight infants. Research studies and program implementation of KMC have used various definitions.

  1. Nonlinear optical imaging characteristics in rat tail tendon

    Science.gov (United States)

    Liu, N. R.; Zhang, X. Z.; Qiu, Y. S.; Chen, R.

    2013-04-01

    The aim of this study was to examine the characteristics of skeletal muscle fibers in tail tendons, explore the content of intrinsic components at different depths and ascertain the optimum excitation wavelength, which will help to establish a relationship between diagnosis and therapy and the tendon injury. A multiphoton microscopic imaging system was used to achieve the images and spectra via an imaging mode and a Lambda mode, respectively. This work demonstrates that the skeletal muscle fibers of the tail tendon are in good order. Second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals originating from certain intrinsic components are varied with depth, and the SHG/TPEF intensity ratios are varied at different excitation wavelengths. Below 800 nm is the optimum for cell TPEF, while above 800 nm is the optimum for SHG. With the development of imaging techniques, a nonlinear optical imaging system will be helpful to represent the functional behaviors of tissue related to tendon injury.

  2. Kangaroo Care: Experiences and Needs of Parents in Neonatal Intensive Care: A Systematic Review ‘Parents’ Experience of Kangaroo Care’

    NARCIS (Netherlands)

    Gabriels, karlijn; Brouwer, AJ; maat, Jessica; van den Hoogen, Agnes

    2015-01-01

    Abstract This review is focusing on the experiences and needs of parents with infants within NICU regarding Kangaroo Care. Ten studies with qualitative designs were included. Kangaroo Care was overall experienced as positive; giving parents the opportunity to get to know their babies and (re-) const

  3. Modeling the Nonlinear Motion of the Rat Central Airways.

    Science.gov (United States)

    Ibrahim, G; Rona, A; Hainsworth, S V

    2016-01-01

    Advances in volumetric medical imaging techniques allowed the subject-specific modeling of the bronchial flow through the first few generations of the central airways using computational fluid dynamics (CFD). However, a reliable CFD prediction of the bronchial flow requires modeling of the inhomogeneous deformation of the central airways during breathing. This paper addresses this issue by introducing two models of the central airways motion. The first model utilizes a node-to-node mapping between the discretized geometries of the central airways generated from a number of successive computed tomography (CT) images acquired dynamically (without breath hold) over the breathing cycle of two Sprague-Dawley rats. The second model uses a node-to-node mapping between only two discretized airway geometries generated from the CT images acquired at end-exhale and at end-inhale along with the ventilator measurement of the lung volume change. The advantage of this second model is that it uses just one pair of CT images, which more readily complies with the radiation dosage restrictions for humans. Three-dimensional computer aided design geometries of the central airways generated from the dynamic-CT images were used as benchmarks to validate the output from the two models at sampled time-points over the breathing cycle. The central airway geometries deformed by the first model showed good agreement to the benchmark geometries within a tolerance of 4%. The central airway geometry deformed by the second model better approximated the benchmark geometries than previous approaches that used a linear or harmonic motion model.

  4. Reproductive strategies of the kangaroo leech, Marsupiobdella africana (Glossiphoniidae

    Directory of Open Access Journals (Sweden)

    Natasha Kruger

    2015-04-01

    Full Text Available The Kangaroo Leech, Marsupiobdella africana, is a hermaphroditic organism, with insemination taking place by the planting of a spermatophore on another leech. Spermatophores are mostly planted on the anterior of the recipient leech, but not always. Several spermatophores may be planted by different leeches on a single recipient. The spermatophore consists of two side by side lobes. Within minutes from planting of the spermatophore, the contents are squeezed out and into the body of the recipient. Sperm are believed to find the way to the ova by following chemical cues. Kangaroo Leeches display advanced parental care by transferring fertilized eggs from the reproductive opening to a brood pouch on the ventral side. Fully developed leeches may copulate after detaching from the amphibian host Xenopus laevis, or from the Cape River Crab Potamonautes perlatus with which it maintains a phoretic association.

  5. Peters anomaly in a red kangaroo (Macropus rufus).

    Science.gov (United States)

    Suedmeyer, Wm Kirk; Pearce, Jacqueline; Persky, Meredith; Houck, Marlys L

    2014-09-01

    A 10-mo-old female red kangaroo (Macropus rufus) presented with a unilateral congenital corneal opacity OD. Complete ophthalmic examination revealed a shallow anterior chamber and a focal area of corneal edema with multiple persistent pupillary membranes extending from the iris colarette to the corneal endothelium adjacent to the edematous area of cornea. High-resolution B-scan ultrasound of the anterior segment showed an area consistent with thinning of Descemet's membrane in the area of corneal edema. Ophthalmic examination and ultrasound findings are consistent with a diagnosis of Peters anomaly, a form of anterior segment dysgenesis. An electroretinogram performed on the affected animal did not reveal any specific abnormalities. Karyotype analyses revealed a normal diploid number (2n = 20, -XX), with an abnormal pericentric inversion in the second largest chromosomal pair. The kangaroo exhibits mild compensated vision deficits in the affected eye. The maternal and paternal adult pairing has been discontinued in an effort to prevent future offspring anomalies.

  6. Kangaroo Mother Method: Mothers' Experiences and Contributions to Nursing

    OpenAIRE

    João Carlos Arivabene; Maria Antonieta Rubio Tyrrell

    2010-01-01

    This research aimed to describe mothers' experiences, analyzing them in the light of the principles of the Kangaroo Mother Method (KMM), and discuss the mothers' contributions based on the meanings of these experiences for nursing actions. In data collection, a questionnaire was used that characterized the mothers' socioeconomic profile and, through focus groups, stories were obtained about the benefits of these experiences, which supported the construction of the following categories: surviv...

  7. Kangaroo – A pattern-matching program for biological sequences

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    Betel Doron

    2002-07-01

    Full Text Available Abstract Background Biologists are often interested in performing a simple database search to identify proteins or genes that contain a well-defined sequence pattern. Many databases do not provide straightforward or readily available query tools to perform simple searches, such as identifying transcription binding sites, protein motifs, or repetitive DNA sequences. However, in many cases simple pattern-matching searches can reveal a wealth of information. We present in this paper a regular expression pattern-matching tool that was used to identify short repetitive DNA sequences in human coding regions for the purpose of identifying potential mutation sites in mismatch repair deficient cells. Results Kangaroo is a web-based regular expression pattern-matching program that can search for patterns in DNA, protein, or coding region sequences in ten different organisms. The program is implemented to facilitate a wide range of queries with no restriction on the length or complexity of the query expression. The program is accessible on the web at http://bioinfo.mshri.on.ca/kangaroo/ and the source code is freely distributed at http://sourceforge.net/projects/slritools/. Conclusion A low-level simple pattern-matching application can prove to be a useful tool in many research settings. For example, Kangaroo was used to identify potential genetic targets in a human colorectal cancer variant that is characterized by a high frequency of mutations in coding regions containing mononucleotide repeats.

  8. Magnetic resonance imaging findings in a red kangaroo (Macropus rufus) with otitis.

    Science.gov (United States)

    Okeson, Danelle M; Coke, Rob L; Kochunov, Peter; Davis, M Duff

    2008-12-01

    Magnetic resonance imaging (MRI) was performed on an adult, male Red kangaroo (Macropus rufus) with a history of nonspecific neurologic signs and acute discharge from the left ear. MRI revealed findings consistent with otitis and possible osteomyelitis of the temporal and mastoid bones. To the authors' knowledge, this is the first report of otitis and MRI findings in a kangaroo.

  9. Three-dimensional ankle moments and nonlinear summation of rat triceps surae muscles.

    Science.gov (United States)

    Tijs, Chris; van Dieën, Jaap H; Baan, Guus C; Maas, Huub

    2014-01-01

    The Achilles tendon and epimuscular connective tissues mechanically link the triceps surae muscles. These pathways may cause joint moments exerted by each muscle individually not to sum linearly, both in magnitude and direction. The aims were (i) to assess effects of sagittal plane ankle angle (varied between 150° and 70°) on isometric ankle moments, in both magnitude and direction, exerted by active rat triceps surae muscles, (ii) to assess ankle moment summation between those muscles for a range of ankle angles and (iii) to assess effects of sagittal plane ankle angle and muscle activation on Achilles tendon length. At each ankle angle, soleus (SO) and gastrocnemius (GA) muscles were first excited separately to assess ankle-angle moment characteristics and subsequently both muscles were excited simultaneously to investigate moment summation. The magnitude of ankle moment exerted by SO and GA, the SO direction in the transverse and sagittal planes, and the GA direction in the transverse plane were significantly affected by ankle angle. SO moment direction in the frontal and sagittal planes were significantly different from that of GA. Nonlinear magnitude summation varied between 0.6±2.9% and -3.6±2.9%, while the nonlinear direction summation varied between 0.3±0.4° and -0.4±0.7° in the transverse plane, between 0.5±0.4° and 0.1±0.4° in the frontal plane, and between 3.0±7.9° and 0.3±2.3° in the sagittal plane. Changes in tendon length caused by SO contraction were significantly lower than those during contraction of GA and GA+SO simultaneously. Thus, moments exerted by GA and SO sum nonlinearly both in the magnitude and direction. The limited degree of nonlinear summation may be explained by different mechanisms acting in opposite directions.

  10. Three-dimensional ankle moments and nonlinear summation of rat triceps surae muscles.

    Directory of Open Access Journals (Sweden)

    Chris Tijs

    Full Text Available The Achilles tendon and epimuscular connective tissues mechanically link the triceps surae muscles. These pathways may cause joint moments exerted by each muscle individually not to sum linearly, both in magnitude and direction. The aims were (i to assess effects of sagittal plane ankle angle (varied between 150° and 70° on isometric ankle moments, in both magnitude and direction, exerted by active rat triceps surae muscles, (ii to assess ankle moment summation between those muscles for a range of ankle angles and (iii to assess effects of sagittal plane ankle angle and muscle activation on Achilles tendon length. At each ankle angle, soleus (SO and gastrocnemius (GA muscles were first excited separately to assess ankle-angle moment characteristics and subsequently both muscles were excited simultaneously to investigate moment summation. The magnitude of ankle moment exerted by SO and GA, the SO direction in the transverse and sagittal planes, and the GA direction in the transverse plane were significantly affected by ankle angle. SO moment direction in the frontal and sagittal planes were significantly different from that of GA. Nonlinear magnitude summation varied between 0.6±2.9% and -3.6±2.9%, while the nonlinear direction summation varied between 0.3±0.4° and -0.4±0.7° in the transverse plane, between 0.5±0.4° and 0.1±0.4° in the frontal plane, and between 3.0±7.9° and 0.3±2.3° in the sagittal plane. Changes in tendon length caused by SO contraction were significantly lower than those during contraction of GA and GA+SO simultaneously. Thus, moments exerted by GA and SO sum nonlinearly both in the magnitude and direction. The limited degree of nonlinear summation may be explained by different mechanisms acting in opposite directions.

  11. The physics of articulated toys - a jumping and rotating kangaroo

    CERN Document Server

    Güémez, J

    2014-01-01

    We describe the physics of an articulated toy with an internal source of energy provided by a spiral spring. The toy is a funny low cost kangaroo which jumps and rotates. The study consists of a mechanical and a thermodynamical analysis which makes use of the Newton and center of mass equations, the rotational equations and the first law of thermodynamics. This amazing toy provides a nice demonstrative example how new physics insights can be brought about when links with thermodynamics are established in the study of mechanical systems.

  12. PROPAGATION OF EPILEPTIFORM ACTIVITY DURING DEVELOPMENT OF AMYGDALA KINDLING IN RATS - LINEAR AND NONLINEAR ASSOCIATION BETWEEN IPSILATERAL AND CONTRALATERAL SITES

    NARCIS (Netherlands)

    BELDHUIS, HJA; SUZUKI, T; PIJN, JPM; TEISMAN, A; DASILVA, FHL; BOHUS, B

    1993-01-01

    The relationship between ipsi- and contralateral epileptiform electroencephalographic (EEG) activity was investigated in rats that were kindled daily in the amygdala. Two types of relationship-linear and non-linear associations-were studied and used to estimate time delays of EEG activity between ho

  13. impact of partial kangaroo mother care on growth rates and duration ...

    African Journals Online (AJOL)

    2012-02-02

    Feb 2, 2012 ... rates and duration of hospital stay of Low Birth Weight (LBW) infants. Design: ... Intervention: Kangaroo mother care was practised over an eight hour period per day ... settings, as well as its benefits and limitations. These.

  14. Nurses' adherence to the Kangaroo Care Method: support for nursing care management

    Directory of Open Access Journals (Sweden)

    Laura Johanson da Silva

    2015-06-01

    Full Text Available OBJECTIVE: construct an explanatory theoretical model about nurses' adherence to the Kangaroo Care Method at the Neonatal Intensive Care Unit, based on the meanings and interactions for care management.METHOD: qualitative research, based on the reference framework of the Grounded Theory. Eight nurses were interviewed at a Neonatal Intensive Care Unit in the city of Rio de Janeiro. The comparative analysis of the data comprised the phases of open, axial and selective coding. A theoretical conditional-causal model was constructed.RESULTS: four main categories emerged that composed the analytic paradigm: Giving one's best to the Kangaroo Method; Working with the complexity of the Kangaroo Method; Finding (demotivation to apply the Kangaroo Method; and Facing the challenges for the adherence to and application of the Kangaroo Method.CONCLUSIONS: the central phenomenon revealed that each nurse and team professional has a role of multiplying values and practices that may or may not be constructive, potentially influencing the (discontinuity of the Kangaroo Method at the Neonatal Intensive Care Unit. The findings can be used to outline management strategies that go beyond the courses and training and guarantee the strengthening of the care model.

  15. Toxoplasmosis in the Eastern Grey Kangaroo, Macropus giganteus and the Cape Hyrax, Procavis capensis in Japan

    Directory of Open Access Journals (Sweden)

    Khaled Mohamed El-Dakhly1,4, Nagwan El-Habashi2, El-Shaymaa El-Nahass3,4, Hiroki Sakai4 and Tokuma Yanai4,*

    2013-11-01

    Full Text Available Toxoplasmosis was investigated in an eastern grey kangaroo, Macropus giganteus, and four cape hyraxes, Procavia capensis, in a Japanese zoo. Clinically, the kangaroo showed neurological signs, emaciation, diarrhea, elevated AST and CK, and subjected to coma before death. One young cape hyrax had severe anorexia, while the other three died without exhibiting clinical signs. Grossly, lungs of the kangaroo were dark red in color, while hyraxes, besides, showed hepatic multifocal white foci, and intestinal multifocal hemorrhages. Histologically, the kangaroo had frequent Toxoplasma gondii pseudocysts in brain, heart and skeletal muscles. All hyraxes had multifocal necrosis with cysts containing numerous bradyzoites in liver and spleen, along with necrotic gastroenteritis and intestinal hemorrhages. Immunohistochemically, cysts showed positive reaction to anti-T. gondii antibodies. These findings indicate possible outbreaks of toxoplasmosis in eastern grey kangaroos and cape hyraxes, zoo habitants; therefore, they could be susceptible intermediate hosts for T. gondii in terms of zoonosis. This is the first report of toxoplasmosis in eastern grey kangaroos and cape hyraxes in Japanese zoos.

  16. Understanding kangaroo care and its benefits to preterm infants

    Directory of Open Access Journals (Sweden)

    Campbell-Yeo ML

    2015-03-01

    Full Text Available Marsha L Campbell-Yeo,1–4 Timothy C Disher,1 Britney L Benoit,1 C Celeste Johnston,2,4,5 1School of Nursing, Dalhousie University, 2Department of Pediatrics, IWK Health Centre, 3Department of Psychology and Neuroscience, Dalhousie University, 4Centre for Pediatric Pain Research, IWK Health Centre, Halifax, NS, 5Ingram School of Nursing, McGill University, Montréal, QC, Canada Abstract: The holding of an infant with ventral skin-to-skin contact typically in an upright position with the swaddled infant on the chest of the parent, is commonly referred to as kangaroo care (KC, due to its simulation of marsupial care. It is recommended that KC, as a feasible, natural, and cost-effective intervention, should be standard of care in the delivery of quality health care for all infants, regardless of geographic location or economic status. Numerous benefits of its use have been reported related to mortality, physiological (thermoregulation, cardiorespiratory stability, behavioral (sleep, breastfeeding duration, and degree of exclusivity domains, as an effective therapy to relieve procedural pain, and improved neurodevelopment. Yet despite these recommendations and a lack of negative research findings, adoption of KC as a routine clinical practice remains variable and underutilized. Furthermore, uncertainty remains as to whether continuous KC should be recommended in all settings or if there is a critical period of initiation, dose, or duration that is optimal. This review synthesizes current knowledge about the benefits of KC for infants born preterm, highlighting differences and similarities across low and higher resource countries and in a non-pain and pain context. Additionally, implementation considerations and unanswered questions for future research are addressed. Keywords: kangaroo care, skin-to-skin contact, infant, preterm, review

  17. Spatial requirements of free-ranging Huon tree kangaroos, Dendrolagus matschiei (Macropodidae, in upper montane forest.

    Directory of Open Access Journals (Sweden)

    Gabriel Porolak

    Full Text Available Tree kangaroos (Macropodidae, Dendrolagus are some of Australasia's least known mammals. However, there is sufficient evidence of population decline and local extinctions that all New Guinea tree kangaroos are considered threatened. Understanding spatial requirements is important in conservation and management. Expectations from studies of Australian tree kangaroos and other rainforest macropodids suggest that tree kangaroos should have small discrete home ranges with the potential for high population densities, but there are no published estimates of spatial requirements of any New Guinea tree kangaroo species. Home ranges of 15 Huon tree kangaroos, Dendrolagus matschiei, were measured in upper montane forest on the Huon Peninsula, Papua New Guinea. The home range area was an average of 139.6±26.5 ha (100% MCP; n = 15 or 81.8±28.3 ha (90% harmonic mean; n = 15, and did not differ between males and females. Home ranges of D. matschiei were 40-100 times larger than those of Australian tree kangaroos or other rainforest macropods, possibly due to the impact of hunting reducing density, or low productivity of their high altitude habitat. Huon tree kangaroos had cores of activity within their range at 45% (20.9±4.1 ha and 70% (36.6±7.5 ha harmonic mean isopleths, with little overlap (4.8±2.9%; n = 15 pairs between neighbouring females at the 45% isopleth, but, unlike the Australian species, extensive overlap between females (20.8±5.5%; n = 15 pairs at the complete range (90% harmonic mean. Males overlapped each other and females to a greater extent than did pairs of females. From core areas and overlap, the density of female D. matschiei was one per 19.4 ha. Understanding the cause of this low density is crucial in gaining greater understanding of variations in density of tree kangaroos across the landscape. We consider the potential role of habitat fragmentation, productivity and hunting pressure in limiting tree kangaroo

  18. Interpersonal relationships between professionals and mothers of premature from Kangaroo-Unit

    Directory of Open Access Journals (Sweden)

    Francisca Eliene de Oliveira Callou

    2010-06-01

    Full Text Available Objective: To understand the interpersonal relationships between professionals and mothers of premature newborns of the Kangaroo Unit. Methods: This was an exploratory study of qualitative approach. The interviews were conducted with 10 mothers and 7 professionals who joined in Kangaroo Program and then analyzed by the content analysis technique. The guiding questions used were related to feelings perceived in relation to the Kangaroo method, related to mother-child dyad and interpersonal relationships. Results: Mothers reported on their speeches: “safe to be with the baby in Kangaroo Method” and “sense of maternal feeling during breastfeeding”, while in the professionals’ discourses have emerged: “guidelines on caring for the babies”, “the embracement by the team” and “the importance of family support.” Conclusions: The interaction between professionals and mothers of Kangaroo Unit facilitates the permanence of the binomial in the method, therefore develops feelings of security, tranquility and confidence to take care of the baby. It is important that the team be aware of the difficulties, supporting them in the weakest moments and sharing their fears, doubts and concerns over the baby’s hospitalization.

  19. Multi-proxy monitoring approaches at Kangaroo Island, South Australia

    Science.gov (United States)

    Dixon, Bronwyn; Drysdale, Russell; Tyler, Jonathan; Goodwin, Ian

    2017-04-01

    Interpretations of geochemical signals preserved in young speleothems are greatly enhanced by comprehensive cave-site monitoring. In the light of this, a cave monitoring project is being conducted concurrently with the development of a new palaeoclimate record from Kelly Hill Cave (Kangaroo Island, South Australia). The site is strategically located because it is situated between longer-lived monitoring sites in southeastern and southwestern Australia, as well as being climatically 'upstream' from major population and agricultural centres. This study aims to understand possible controls on speleothem δ18O in Kelly Hill Cave through i. identification of local and regional δ18O drivers in precipitation; and ii. preservation and modification of climatic signals within the epikarst as indicated by dripwater δ18O. These aims are achieved through analysis of a five-year daily rainfall (amount and δ18O) dataset in conjunction with in-cave drip monitoring. Drivers of precipitation δ18O were identified through linear regression between δ18O values and local meteorological variables, air-parcel back trajectories, and synoptic-typing. Synoptically driven moisture sources were identified through the use of NCEP/NCAR climate reanalysis sea-level pressure, precipitable moisture, and outgoing longwave radiation data in order to trace moisture sources and travel mechanisms from surrounding ocean basins. Local controls on δ18O at Kelly Hill Cave are consistent with published interpretations of southern Australia sites, with oxygen isotopes primarily controlled by rainfall amount on both daily and monthly time scales. Back-trajectory analysis also supports previous observations that the Southern Ocean is the major source for moisture-bearing cold-front systems. However, synoptic typing of daily rainfall δ18O and amount extremes reveals a previously unreported tropical connection and moisture source. This tropical connection appears to be strongest in summer and autumn, but

  20. Advantages of kangaroo Mother care in Less Than 2000 Grams Low Birth Weight Neonates

    Directory of Open Access Journals (Sweden)

    Mohsen Jafarzadeh

    2011-05-01

    Full Text Available Background:The aim of study was to compare the effect of Kangaroo mother care (KMC and conventional methods of care (CMC in low birth weight babies less than 2000 grams.Method: One hundred babies with birth weight less than 2000 grams and without clinical problem were randomized in two groups; the tervention group (N=50 who received Kangaroo mother care and the control group (N=50 with conventional care. Two groups were compared in daily weight gaining, self confidence of mother, duration of hospitalization, clinical cyanosis and nosocomial infection. Collected data was analyzed by SPSS 11.5 software . Irct ID: IRCT201101091162N16.Results: The KMC babies had better daily weight gaining average [18.31±7.57gm vs. 4.8±16.57gm (P0.05.Conclusions: In this study Kangaroo mother care had better effect on daily weight gaining, mother confidence and shorter duration of hospitalization.

  1. Physical mechanisms underlying the strain-rate-dependent mechanical behavior of kangaroo shoulder cartilage

    Science.gov (United States)

    Thibbotuwawa, Namal; Oloyede, Adekunle; Li, Tong; Singh, Sanjleena; Senadeera, Wijitha; Gu, YuanTong

    2015-09-01

    Due to anatomical and biomechanical similarities to human shoulder, kangaroo was chosen as a model to study shoulder cartilage. Comprehensive enzymatic degradation and indentation tests were applied on kangaroo shoulder cartilage to study mechanisms underlying its strain-rate-dependent mechanical behavior. We report that superficial collagen plays a more significant role than proteoglycans in facilitating strain-rate-dependent behavior of the kangaroo shoulder cartilage. By comparing the mechanical properties of degraded and normal cartilages, it was noted that proteoglycan and collagen degradation significantly compromised strain-rate-dependent mechanical behavior of the cartilage. Superficial collagen contributed equally to the tissue behavior at all strain-rates. This is different to the studies reported on knee cartilage and confirms the importance of superficial collagen on shoulder cartilage mechanical behavior. A porohyperelastic numerical model also indicated that collagen disruption would lead to faster damage of the shoulder cartilage than when proteoglycans are depleted.

  2. Parental involvement and kangaroo care in European neonatal intensive care units

    DEFF Research Database (Denmark)

    Pallás-Alonso, Carmen R; Losacco, Valentina; Maraschini, Alice

    2012-01-01

    To compare, in a large representative sample of European neonatal intensive care units, the policies and practices regarding parental involvement and holding babies in the kangaroo care position as well as differences in the tasks mothers and fathers are allowed to carry out....

  3. Phylogeography of Eastern Grey Kangaroos, Macropus giganteus, Suggests a Mesic Refugium in Eastern Australia.

    Directory of Open Access Journals (Sweden)

    Brett A Coghlan

    Full Text Available Phylogeographic studies around the world have identified refugia where fauna were able to persist during unsuitable climatic periods, particularly during times of glaciation. In Australia the effects of Pleistocene climate oscillations on rainforest taxa have been well studied but less is known about the effects on mesic-habitat fauna, such as the eastern grey kangaroo (Macropus giganteus. The eastern grey kangaroo is a large mammal that is common and widespread throughout eastern Australia, preferring dry mesic habitat, rather than rainforest. As pollen evidence suggests that the central-eastern part of Australia (southeast Queensland and northern New South Wales experienced cycles of expansion in mesic habitat with contraction in rainforests, and vice versa during glacial and interglacial periods, respectively, we hypothesise that the distribution of the eastern grey kangaroo was affected by these climate oscillations and may have contracted to mesic habitat refugia. From 375 mitochondrial DNA control region sequences from across the distribution of eastern grey kangaroos we obtained 108 unique haplotypes. Phylogenetic analysis identified two clades in Queensland, one of which is newly identified and restricted to a small coastal region in southern Queensland north of Brisbane, known as the Sunshine Coast. The relatively limited geographic range of this genetically isolated clade suggests the possibility of a mesic habitat refugium forming during rainforest expansion during wetter climate cycles. Other potential, although less likely, reasons for the genetic isolation of the highly distinct clade include geographic barriers, separate northward expansions, and strong local adaptation.

  4. Functional morphology of the forelimb of living and extinct tree-kangaroos (Marsupialia: Macropodidae).

    Science.gov (United States)

    Warburton, Natalie M; Harvey, Kathryn J; Prideaux, Gavin J; O'Shea, James E

    2011-10-01

    Tree-kangaroos are a unique group of arboreal marsupials that evolved from terrestrial ancestors. The recent discovery of well-preserved specimens of extinct tree-kangaroo species (genus Bohra) within Pleistocene cave deposits of south-central Australia provides a unique opportunity to examine adaptive evolution of tree-kangaroos. Here, we provide the first detailed description of the functional anatomy of the forelimb, a central component of the locomotor complex, in the extant Dendrolagus lumholtzi, and compare its structure and function with representatives of other extant marsupial families. Several features were interpreted as adaptations for coping with a discontinuous, uneven and three-dimensional arboreal substrate through enhanced muscular strength and dexterity for propulsion, grasping, and gripping with the forelimbs. The forelimb musculoskeletal anatomy of Dendrolagus differed from terrestrial kangaroos in the following principal ways: a stronger emphasis on the development of muscles groups responsible for adduction, grasping, and gripping; the enlargement of muscles that retract the humerus; and modified shape of the scapula and bony articulations of the forelimb bones to allow improved mobility. Many of these attributes are convergent with other arboreal marsupials. Tree-kangaroos, however, still retain the characteristic bauplan of their terrestrial ancestors, particularly with regard to skeletal morphology, and the muscular anatomy of the forelimb highlights a basic conservatism within the group. In many instances, the skeletal remains of Bohra have similar features to Dendrolagus that suggest adaptations to an arboreal habit. Despite the irony of their retrieval from deposits of the Nullarbor "Treeless" Plain, forelimb morphology clearly shows that the species of Bohra were well adapted to an arboreal habitat.

  5. Preterm newborns at Kangaroo Mother Care: a cohort follow-up from birth to six months

    Directory of Open Access Journals (Sweden)

    Maria Alexsandra da S. Menezes

    2014-06-01

    Full Text Available OBJECTIVE:To evaluate clinical outcomes, growth and exclusive breastfeeding rates in premature infants assisted by Kangaroo Mother Care at birth, at discharge and at six months of life.METHODS: Prospective study of a premature infants cohort assisted by Kangaroo Mother Care in a tertiary public maternity in Northeast Brazil with birth weight ≤1750g and with clinical conditions for Kangaroo care.RESULTS: The sample was composed by 137 premature infants, being 62.8% female, with average birth weight of 1365±283g, average gestational age of 32±3 weeks and 26.2% were adequate for gestational age. They have been admitted in the Kangaroo Ward with a median of 13 days of life, weighing 1430±167g and, at this time, 57.7% were classified as small for corrected gestational age. They were discharged with 36.8±21.8 days of chronological age, weighing 1780±165g and 67.9% were small for corrected gestational age. At six months of life (n=76, they had an average weight of 5954±971g, and 68.4% presented corrected weight for gestational age between percentiles 15 and 85 of the World Health Organization (WHO weight curve. Exclusive breastfeeding rate at discharge was 56.2% and, at six months of life, 14.4%.CONCLUSIONS: In the studied sample, almost two thirds of the children assisted by Kangaroo Mother Care were, at six months of life, between percentiles 15 and 85 of the WHO weight curves. The frequency of exclusive breastfeeding at six months was low.

  6. Hopping Down the Main Street: Eastern Grey Kangaroos at Home in an Urban Matrix

    Directory of Open Access Journals (Sweden)

    Graeme Coulson

    2014-05-01

    Full Text Available Most urban mammals are small. However, one of the largest marsupials, the Eastern Grey Kangaroo Macropus giganteus, occurs in some urban areas. In 2007, we embarked on a longitudinal study of this species in the seaside town of Anglesea in southern Victoria, Australia. We have captured and tagged 360 individuals to date, fitting each adult with a collar displaying its name. We have monitored survival, reproduction and movements by resighting, recapture and radio-tracking, augmented by citizen science reports of collared individuals. Kangaroos occurred throughout the town, but the golf course formed the nucleus of this urban population. The course supported a high density of kangaroos (2–5/ha, and approximately half of them were tagged. Total counts of kangaroos on the golf course were highest in summer, at the peak of the mating season, and lowest in winter, when many males but not females left the course. Almost all tagged adult females were sedentary, using only part of the golf course and adjacent native vegetation and residential blocks. In contrast, during the non-mating season (autumn and winter, many tagged adult males ranged widely across the town in a mix of native vegetation remnants, recreation reserves, vacant blocks, commercial properties and residential gardens. Annual fecundity of tagged females was generally high (≥70%, but survival of tagged juveniles was low (54%. We could not determine the cause of death of most juveniles. Vehicles were the major (47% cause of mortality of tagged adults. Road-kills were concentrated (74% in autumn and winter, and were heavily male biased: half of all tagged males died on roads compared with only 20% of tagged females. We predict that this novel and potent mortality factor will have profound, long-term impacts on the demography and behavior of the urban kangaroo population at Anglesea.

  7. Circulating levels of prolactin and progesterone in a wild population of red kangaroos (Macropus rufus) Marsupialia: Macropodidae

    Science.gov (United States)

    Muths, E.; Hinds, L. A.

    1996-01-01

    Circulating progesterone and prolactin levels were measured in shot and live-caught wild red kangaroos using radioimmunoassays validated for the red kangaroo. The objective of the study was to correlate hormone profiles with reproductive status and determine if red kangaroos follow the general pattern elucidated for other macropodids. During Phase 2a lactation (600 pg/ml (n= 32) during the transition to Phase 3 lactation (181 to 235 days) when the quiescent corpus luteum and embryo were reactivated. Progesterone concentrations then decreased to prolactin during Phase 2a were prolactin concentrations increased to 15 ng/ml (n= 32), then decreased and remained low through the subsequent stage of dual lactation. These results indicate that progesterone and prolactin profiles in wild red kangaroos follow patterns found previously in other macropodid species, the tammar and Bennett's wallabies.

  8. Comparative nonlinear modeling of renal autoregulation in rats: Volterra approach versus artificial neural networks

    DEFF Research Database (Denmark)

    Chon, K H; Holstein-Rathlou, N H; Marsh, D J

    1998-01-01

    via the Laguerre expansion technique achieve this prediction NMSE with approximately half the number of free parameters relative to either neural-network model. However, both approaches are deemed effective in modeling nonlinear dynamic systems and their cooperative use is recommended in general....

  9. Nonlinear analysis of renal autoregulation in rats using principal dynamic modes

    DEFF Research Database (Denmark)

    Marmarelis, V Z; Chon, K H; Holstein-Rathlou, N H

    1999-01-01

    and collected in normotensive and hypertensive rats for two levels of pressure forcing (as measured by the standard deviation of the pressure fluctuation). The PDMs are computed from first-order and second-order kernel estimates obtained from the data via the Laguerre expansion technique. The results...

  10. Transparency and communication can improve wildlife welfare outcomes: A case of kangaroos

    Directory of Open Access Journals (Sweden)

    Simmons Peter

    2017-01-01

    Full Text Available All countries manage human and wildlife coexistence. Where traditionally humans may have killed animals perceived to be a problem, this is often no longer legal or socially acceptable. Decision-makers tend to feel less strongly about coexistence issues than the people who attempt to influence them on behalf of human or wildlife interests. It has been argued that links between human interests and decisions affecting wildlife should be transparent, and that open decision making processes involving a range of local stakeholders will improve outcomes for humans and wildlife. This paper examines one case incident in an ongoing conflict between an international car racing track and kangaroos that have occasionally been found on the track during a race, causing danger to themselves and race participants. A secret local government report and plan to cull kangaroos was obtained using Freedom of Information legislation. When released to the media the subsequent public discussion showed a much greater concern for kangaroo stress, harm and right to live than the official report, and called for consideration of a range of alternatives to culling. This led to postponement of culling plans, and commitment to a more open community discussion of options. The case clearly supports claims that greater transparency and local stakeholder participation in management decision processes can improve welfare outcomes for non-human animals.

  11. Significance of using a nonlinear analysis technique, the Lyapunov exponent, on the understanding of the dynamics of the cardiorespiratory system in rats.

    Science.gov (United States)

    Zeren, Tamer; Özbek, Mustafa; Kutlu, Necip; Akilli, Mahmut

    2016-01-05

    Pneumocardiography (PNCG) is the recording method of cardiac-induced tracheal air flow and pressure pulsations in the respiratory airways. PNCG signals reflect both the lung and heart actions and could be accurately recorded in spontaneously breathing anesthetized rats. Nonlinear analysis methods, including the Lyapunov exponent, can be used to explain the biological dynamics of systems such as the cardiorespiratory system. In this study, we recorded tracheal air flow signals, including PNCG signals, from 3 representative anesthetized rats and analyzed the nonlinear behavior of these complex signals using Lyapunov exponents. Lyapunov exponents may also be used to determine the normal and pathological structure of biological systems. If the signals have at least one positive Lyapunov exponent, the signals reflect chaotic activity, as seen in PNCG signals in rats; the largest Lyapunov exponents of the signals of the healthy rats were greater than zero in this study. A method was proposed to determine the diagnostic and prognostic values of the cardiorespiratory system of rats using the arrangement of the PNCG and Lyapunov exponents, which may be monitored as vitality indicators.

  12. Physiologically based pharmacokinetic model for ethyl tertiary-butyl ether and tertiary-butyl alcohol in rats: Contribution of binding to α2u-globulin in male rats and high-exposure nonlinear kinetics to toxicity and cancer outcomes.

    Science.gov (United States)

    Borghoff, Susan J; Ring, Caroline; Banton, Marcy I; Leavens, Teresa L

    2017-05-01

    In cancer bioassays, inhalation, but not drinking water exposure to ethyl tertiary-butyl ether (ETBE), caused liver tumors in male rats, while tertiary-butyl alcohol (TBA), an ETBE metabolite, caused kidney tumors in male rats following exposure via drinking water. To understand the contribution of ETBE and TBA kinetics under varying exposure scenarios to these tumor responses, a physiologically based pharmacokinetic model was developed based on a previously published model for methyl tertiary-butyl ether, a structurally similar chemical, and verified against the literature and study report data. The model included ETBE and TBA binding to the male rat-specific protein α2u-globulin, which plays a role in the ETBE and TBA kidney response observed in male rats. Metabolism of ETBE and TBA was described as a single, saturable pathway in the liver. The model predicted similar kidney AUC0-∞ for TBA for various exposure scenarios from ETBE and TBA cancer bioassays, supporting a male-rat-specific mode of action for TBA-induced kidney tumors. The model also predicted nonlinear kinetics at ETBE inhalation exposure concentrations above ~2000 ppm, based on blood AUC0-∞ for ETBE and TBA. The shift from linear to nonlinear kinetics at exposure concentrations below the concentration associated with liver tumors in rats (5000 ppm) suggests the mode of action for liver tumors operates under nonlinear kinetics following chronic exposure and is not relevant for assessing human risk. Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

  13. The Effect of Kangaroo Mother Care on Fuss and Crying Time in Colicky Infants

    Directory of Open Access Journals (Sweden)

    Zahra Akbarian Rad

    2015-03-01

    Full Text Available Background: Infantile colic is a common complaint in the first few weeks of life. On the other hand, because of its unknown etiology, there is not a specific therapy for this complaint, but various therapeutic options for reducing pain and restlessness of these infants are recommended. Skin to skin contact by Kangaroo Mother Care (KMC increases in pain threshold and it seems to be a suitable method for the care of these infants. This study was designed to evaluate the effect of KMC on infantile colic. Methods: This case- control study was performed between March 2012 and March 2013. Subjects were 55 infants with exclusive breast fed infant, aged 15-60 days with excessive fuss and crying, referred to Infant and Child Clinic in Ayatollah Rohani Hospital in Babol, north of Iran. Babies whose weights were less than 2500 Grams and with inheritance and clinical diseases excluded from the study. Infants were subjected to KMC at least 2 hours a day. Standard questionnaire and Barr Scale were filled by interview. Data was analyzed by SPSS v.11.5 and T-test, a P- value less than 0.05 considered being significant. Results: The fuss and crying time before the KMC was 2.21±1.54 hours per day and decreased to 1.16±1.3 hours per day after the implementation of KMC. (p=0.001 Conclusions: Kangaroo mother care at home can be used as a simple and safe method for decreasing of cry and fussiness in colicky infants. Keywords: Kangaroo Mother Care (KMC, fussiness, Colicky Infants, colic

  14. The Effect of Kangaroo Mother Care on Fuss and Crying Time in Colicky Infants

    Directory of Open Access Journals (Sweden)

    Zahra Akbarian Rad

    2015-03-01

    Full Text Available AbstractBackground: Infantile colic is a common complaint in the first few weeks of life. On the other hand, because of its unknown etiology, there is not a specific therapy for this complaint, but various therapeutic options for reducing pain and restlessness of these infants are recommended. Skin to skin contact by Kangaroo Mother Care (KMC increases in pain threshold and it seems to be a suitable method for the care of these infants. This study was designed to evaluate the effect of KMC on infantile colic.Methods: This case- control study was performed between March 2012 and March 2013. Subjects were 55 infants with exclusive breast fed infant, aged 15-60 days with excessive fuss and crying, referred to Infant and Child Clinic in Ayatollah Rohani Hospital in Babol, north of Iran. Babies whose weights were less than 2500 Grams and with inheritance and clinical diseases excluded from the study. Infants were subjected to KMC at least 2 hours a day. Standard questionnaire and Barr Scale were filled by interview. Data was analyzed by SPSS v.11.5 and T-test, a P- value less than 0.05 considered being significant.Results:The fuss and crying time before the KMC was 2.21±1.54 hours per day and decreased to 1.16±1.3 hours per day after the implementation of KMC. (p=0.001Conclusions:Kangaroo mother care at home can be used as a simple and safe method for decreasing of cry and fussiness in colicky infants. Keywords: Kangaroo Mother Care (KMC, fussiness, Colicky Infants, colic

  15. A Reproductive Management Program for an Urban Population of Eastern Grey Kangaroos (Macropus giganteus

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    Andrew Tribe

    2014-09-01

    Full Text Available Traditionally, culling has been the expedient, most common, and in many cases, the only tool used to control free-ranging kangaroo populations. We applied a reproductive control program to a population of eastern grey kangaroos confined to a golf course in South East Queensland. The program aimed to reduce fecundity sufficiently for the population to decrease over time so that overgrazing of the fairways and the frequency of human–animal conflict situations were minimised. In 2003, 92% of the female kangaroos above 5 kg bodyweight were implanted with the GnRH agonist deslorelin after darting with a dissociative anaesthetic. In 2007, 86% of the females above 5 kg were implanted with deslorelin and also 87% of the males above 5 kg were sterilised by either orchidectomy or vasectomy. In 2005, 2008 and 2009, the population was censused to assess the effect of each treatment. The 2003 deslorelin program resulted in effective zero population growth for approximately 2.5 years. The combined deslorelin–surgery program in 2007 reduced the birth rate from 0.3 to 0.06%/year for 16 months, resulting in a 27% population reduction by November 2009. The results were consistent with implants conferring contraception to 100% of implanted females for at least 12 months. The iatrogenic mortality rates for each program were 10.5% and 4.9%, respectively, with 50% of all mortalities due to darting-related injuries, exertional myopathy/hyperthermia or recovery misadventure. The short term sexual and agonistic behaviour of the males was assessed for the 2007 program: no significant changes were seen in adult males given the vasectomy procedure, while sexual behaviours’ were decreased in adult males given the orchidectomy procedure. It is concluded that female reproduction was effectively controlled by implantation with deslorrelin and male reproductive behaviour was reduced by orchidectomy, which together achieved population control.

  16. Use of “Kangaroo Care” to Alleviate the Intensity of Vaccination Pain in Newborns

    Directory of Open Access Journals (Sweden)

    Mahboobe Gholami Robatsangi

    2011-03-01

    Full Text Available Objective:It has been demonstrated that newborns feel pain completely. Thus, they should be treated with this in mind. Recent research showed that non-pharmacological interventions such as "Kangaroo Care" may be useful for decreasing pain in newborns. We tried to determine the effect of kangaroo care on the pain intensity of vaccination in healthy newborns. Methods:This study was a randomized case-control clinical trial. Subjects were 60 healthy full-term newborns delivered in a general Hospital, in Iran, from March to July 2006. They were randomly assigned to case and control groups. The case group received 30 minutes skin to skin contact, whereas infants in the control group were put, wrapped in a blanket, aside the mothers. Behavioral changes of newborns were evaluated and observed 2 minutes before, during, and 3 minutes after the intervention. All procedures were filmed. An assistant who was blinded to the study, scored behavior changes using Neonatal/Infant Pain Scale. Heart rate and oxygen saturation levels as displayed on the pulse monitor and duration of crying were recorded using a stopwatch. Findings:Mean pain intensity during the intervention v was significantly lower in the case group (P<0.006. Mean pain intensity 3 minutes after intervention was also significantly lower in the case group (P<0.021. Mean duration of crying was significantly lower in case group as well (P<0.001. Conclusion:Kangaroo care may be used to decrease pain intensity in newborns undergoing painful procedures.

  17. [Pathology of the digestive tract in kangaroos. A review based on our own study results].

    Science.gov (United States)

    Schoon, H A; Murmann, W

    1985-01-01

    The present paper describes spontaneous pathological findings including etiological aspects in digestive tracts of kangaroos, which have been detected in 166 necropsies during the last 20 years. Protozoan - infections, herpes virus infections, gastroenteritis of unknown etiology and especially the occurrence of the so called "lumpy-jaw" turned out to be of special importance. These findings are discussed with reference to the literature, completed as well by short literature reviews, sub-divided into the different organs and the variable etiology of the diseases, as by a brief description of digestive tract physiology and anatomy in marsupials.

  18. Effect of Kangaroo Mother Care on Growth and Morbidity Pattern in Low Birth Weight Infants

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    Keerti Swarnkar

    2016-01-01

    Full Text Available Background: Kangaroo Mother Care (KMC is dened as skin-to-skin contact between a mother and her newborn baby derived from practical similarities to marsupial care giving, proximately exclusive breastfeeding and early discharge from hospital. This concept was proposed as an alternative to conventional methods of care for low birth weight (LBW infants, and in replication to quandaries of earnest overcrowding in Neonatal Intensive Care Units (NICUs. KMC essentially utilizes the mother as a natural incubator Aim and Objectives: The aim was to assess the feasibility, acceptability and the effectiveness of KMC in LBW infants. It avoids agitation routinely experienced in busy ward. Material and Methods: A pilot open-labeled quasi-randomised clinical trial was conducted in Level III NICU of a teaching institution. 60 newborn infants <2500 g, meeting inclusion criteria were alternatively randomised into two groups: Kangaroo Mother Care (KMC and Conventional Methods of Care (CMC. Kangaroo mother care was practiced with minimum total period of eight hours a day intermittently for the intervention group while the controls remained in incubators or cots. Weight, head circumference, length, morbidity episodes, hospital stay, feeding patterns were monitored for all infants till postmenstrual age of 42 weeks in preterm babies or till a weight of 2500 g is achieved in term SGA babies. Results: The pilot study conrmed that trial processes were efcient, the intervention was acceptable (to mothers and nurses and that the outcome measures were appropriate; KMC babies achieved signicantly better growth at the end of the study (For preterm babies, weight, length and head circumference gain were signicantly higher in the KMC group (weight 19.28±2.9g/day, length 0.99±0.56cm/week and head circumference 0.72±0.07 cm/week than in the CMC group (P <0.001. A signicantly higher number of babies in the CMC group suffered from hypothermia, hypoglycemia, and

  19. Plasma endotoxin activity in kangaroos with oral necrobacillosis (lumpy jaw disease) using an automated handheld testing system.

    Science.gov (United States)

    Sotohira, Yukari; Suzuki, Kazuyuki; Sasaki, Haruka; Sano, Tadashi; Tsuchiya, Masakazu; Suzuki, Yohko; Shimamori, Toshio; Tsukano, Kenji; Sato, Ayano; Yokota, Hiroshi; Asakawa, Mitsuhiko

    2016-07-01

    The aim of the present study was to evaluate the reliability and effectiveness of directly determining endotoxin activity in plasma samples from kangaroos with lumpy jaw disease (LJD, n=15) and healthy controls (n=12). Prior to the present study, the ability of the commercially available automated handheld portable test system (PTS(TM)) to detect endotoxin activity in kangaroo plasma was compared with that of the traditional LAL-kinetic turbidimetric (KT) assay. Plasma samples, which were obtained from endotoxin-challenged cattle, were diluted 1:20 in endotoxin-free water and heated to 80°C for 10 min. The performance of the PTS(TM) was not significantly different from that of the traditional LAL-based assay. The data obtained using PTS(TM) correlated with those using KT (r(2)=0.963, PPTS(TM) is applicable as a simplified system to assess endotoxin activity in macropods. In the present study, we demonstrated the diagnostic value of plasma endotoxin activity in kangaroos with systemic inflammation caused by oral necrobacillosis and identified plasma endotoxin activity as a sensitive marker of systemic inflammation in kangaroos with LJD. Based on ROC curves, we proposed a diagnostic cut-off point for endotoxin activity of >0.22 EU/ml for the identification of LJD. Our results indicate that the assessment of plasma endotoxin activity is a promising diagnostic tool for determining the outcome of LJD in captive macropods.

  20. Seasonal variation in kangaroo tooth enamel oxygen and carbon isotopes in southern Australia

    Science.gov (United States)

    Brookman, Tom H.; Ambrose, Stanley H.

    2012-09-01

    Serial sampling of tooth enamel growth increments for carbon and oxygen isotopic analyses of Macropus (kangaroo) teeth was performed to assess the potential for reconstructing paleoseasonality. The carbon isotope composition of tooth enamel apatite carbonate reflects the proportional intake of C3 and C4 vegetation. The oxygen isotopic composition of enamel reflects that of ingested and metabolic water. Tooth enamel forms sequentially from the tip of the crown to the base, so dietary and environmental changes during the tooth's formation can be detected. δ13C and δ18O values were determined for a series of enamel samples drilled from the 3rd and 4th molars of kangaroos that were collected along a 900 km north-south transect in southern Australia. The serial sampling method did not yield pronounced seasonal isotopic variation patterns in Macropus enamel. The full extent of dietary isotopic variation may be obscured by attenuation of the isotopic signal during enamel mineralisation. Brachydont (low-crowned) Macropus teeth may be less sensitive to seasonal variation in isotopic composition due to time-averaging during mineralisation. However, geographic variations observed suggest that there may be potential for tracking latitudinal shifts in vegetation zones and seasonal environmental patterns in response to climate change.

  1. Studies on the in vitro cultivation of ciliate protozoa from the kangaroo forestomach.

    Science.gov (United States)

    Dehority, Burk A; Wright, André-Denis G

    2014-08-01

    The methods used for culturing rumen protozoa were found to be unsatisfactory for growth of ciliate protozoa from the kangaroo forestomach. Based on published measurements of physical parameters in the marsupial forestomach, several modifications were incorporated into the procedure, i.e., an increase in % hydrogen in the gas phase, adjustment of initial pH of the medium to 6.9-7.0 range, feed only forage as a substrate and incubate at a lower temperature (33-36 °C). Only incubation at the lower temperature increased survival time of the kangaroo protozoa. Two species of Bitricha were still viable after 28 d in culture. Cultures had to be terminated at that time. One of the species differed considerably in size and shape from previously described species and based on 18S rRNA data, may represent a new species of Bitricha. The second species, present in low numbers was identified as Bitricha oblata. In a separate trial, Macropodinium yalanbense survived for 11 d, at which time these cultures also had to be terminated. Copyright © 2014 Elsevier GmbH. All rights reserved.

  2. Morphological and morphometric characteristics of gastric mucosa in western grey kangaroo (Macropus fuliginosus

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    Mahmoud Badran Shoeib

    2015-03-01

    Full Text Available The present study was aimed to investigate the morphology and histomorphometry of stomach and gastric mucosa in western grey kangaroo (Macropus fuliginosus. The stomach was composed of three indistinctive separate parts namely sacciform forestomach, tubiform forestomach, and hindstomach. The tubiform forestomach was the main tubular section of the organ. The stomach had a compound lining. The non-glandular mucosa occupied the medial blind sac (MBS of the sacciform forestomach; the layer covered about one-third of the tubiform forestomach (non-glandular region and the entire length of the gastric sulcus. The glandular part lined the parietal blind sac (PBS of sacciform forestomach and the cardiac gland region of tubiform forestomach as well as fundic and pyloric gland regions of the hindstomach. The cardiac mucosa had smooth and folded areas; these were filled with mixed glands. In the fundic glands, the parietal cells outnumbered the chief cells. The pyloric glands were of serous-like in characteristics. In conclusion, gross and histological structures of the stomach of western grey kangaroo are adaptive with its food habitat, which allows thorough mixing of highly fibrous grasses.

  3. Parents’ lived experience of providing kangaroo care to their preterm infants

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    Angela Leonard

    2008-12-01

    Full Text Available Premature and low birthweight infants pose particular challenges to health services in South Africa. While there is good evidence to demonstrate the benefits of kangaroo care in low birthweight infants, limited research has been conducted locally on the experiences of parents who provide kangaroo care to their preterm infants. This phenomenological study explores the lived experience of parents who provided their preterm infants with kangaroo care at a tertiary-level maternity centre in the Western Cape. In-depth interviews were conducted with six parents: four mothers and two fathers. Data was analysed using an adaptation of the approaches described by Colaizzi (1978:48-71 and Hycner (1985:280-294. To ensure trustworthiness, the trustworthiness criteria described by Guba and Lincoln (1989:242-243 were applied. Kangaroo care is a phased process, each phase bringing a unique set of experiences. The eight themes that emerged are described: unforeseen, unprepared and uncertain - the experience of birth; anxiety and barriers; an intimate connection; adjustments, roles and responsibilities; measuring success; a network of encouragement and support; living-in challenges; and living with the infant outside of hospital. Challenges facing health care providers are described and recommendations for information about kangaroo care and support for parents are made. Opsomming Vroeggebore babas en babas met ’n lae geboortegewig stel besondere uitdagings vir Suid-Afrikaanse gesondhiedsdienste. Daar bestaan goeie bewyse dat die kangaroesorgmetode voordelig is vir babas met ’n laegeboortegewig, dog is minimale plaaslike navorsing gedoen oor die ondervindinge van ouers wat hierdie metode gebruik om vir hul vroeggebore babas te sorg. Hierdie fenomenologiese studie verken die geleefde ervaringe van ouers wat vir hulle vroeggebore babas deur middel van die kangaroesorgmetode in ’n tersiêre kraamsentrum in die Weskaap gesorg het. Data is ingesamel deur in

  4. The effect of kangaroo ward care in comparison with "intermediate intensive care" on the growth velocity in preterm infant with birth weight control trial.

    Science.gov (United States)

    Sharma, Deepak; Murki, Srinivas; Pratap, Oleti Tejo

    2016-10-01

    Kangaroo mother care (KMC) reduces neonatal mortality, neonatal sepsis and improves growth outcome in preterm infants. In this study, we compared the efficacy of "baby care in kangaroo ward (KWC)" with "baby care in intermediate intensive care (IIC)" in stable preterm infants (birth weight birth weight <1100 g) infants at term gestational age. Clinical trial registry of India CTRI/2014/05/004625 WHAT IS KNOWN: • Kangaroo mother care (KMC) reduces neonatal mortality, neonatal sepsis and improves growth outcome in VLBW infants. What is new: • Baby care by mother can be given safely in kangaroo ward from a weight of 1150 g in stable preterm infants without any adverse effects.

  5. [Social representations on breastfeeding according to preterm infants' mothers in Kangaroo Care].

    Science.gov (United States)

    Javorski, Marly; Caetano, Laise Conceição; Vasconcelos, Maria Gorete Lucena de; Leite, Adriana Moraes; Scochi, Carmen Gracinda Silvan

    2004-01-01

    This study aimed to identify the social representations on premature infants' breastfeeding at a Kangaroo Care Unit, from the perspective of mothers who are breastfeeding and describe the conflicts and contradictions they experience in this context. A qualitative approach was adopted, using the first stage of enunciation analysis in the light of social representations theory to identify the meanings assigned to breastfeeding. We found the following representations: healthy babies are breastfed, mother's milk provides protection and preserves the premature child's life, breastfeeding is the complement of motherhood and breastfeeding a premature infant is a hard and exhausting experience. The conflicts resulted from the assimilation of technical contents and discourse, late sucking and representations on breastfeeding.

  6. Camels, Cormorants, and Kangaroo Rats: Integration and Synthesis in Organismal Biology After World War II.

    Science.gov (United States)

    Hagen, Joel B

    2015-01-01

    During the decades following World War II diverse groups of American biologists established a variety of distinctive approaches to organismal biology. Rhetorically, organismal biology could be used defensively to distinguish established research traditions from perceived threats from newly emerging fields such as molecular biology. But, organismal biologists were also interested in integrating biological disciplines and using a focus on organisms to synthesize levels of organization from molecules and cells to populations and communities. Part of this broad movement was the development of an area of research variously referred to as physiological ecology, environmental physiology, or ecophysiology. This area of research was distinctive in its self-conscious blend of field and laboratory practices and its explicit integration with other areas of biology such as ecology, animal behavior, and evolution in order to study adaptation. Comparing the intersecting careers of Knut Schmidt-Nielsen and George Bartholomew highlights two strikingly different approaches to physiological ecology. These alternative approaches to studying the interactions of organisms and environments also differed in important ways from the organismal biology championed by leading figures in the modern synthesis.

  7. Brain thermal inertia, but no evidence for selective brain cooling, in free-ranging western grey kangaroos (Macropus fuliginosus).

    Science.gov (United States)

    Maloney, Shane K; Fuller, Andrea; Meyer, Leith C R; Kamerman, Peter R; Mitchell, Graham; Mitchell, Duncan

    2009-04-01

    Marsupials reportedly can implement selective brain cooling despite lacking a carotid rete. We measured brain (hypothalamic) and carotid arterial blood temperatures every 5 min for 5, 17, and 63 days in spring in three free-living western grey kangaroos. Body temperature was highest during the night, and decreased rapidly early in the morning, reaching a nadir at 10:00. The highest body temperatures recorded occurred sporadically in the afternoon, presumably associated with exercise. Hypothalamic temperature consistently exceeded arterial blood temperature, by an average 0.3 degrees C, except during these afternoon events when hypothalamic temperature lagged behind, and was occasionally lower than, the simultaneous arterial blood temperature. The reversal in temperatures resulted from the thermal inertia of the brain; changes in the brain to arterial blood temperature difference were related to the rate of change of arterial blood temperature on both heating and cooling (P cooling in kangaroos. The effect of thermal inertia on brain temperature is larger than might be expected in the grey kangaroo, a discrepancy that we speculate derives from the unique vascular anatomy of the marsupial brain.

  8. Mother-offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos.

    Science.gov (United States)

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-05-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission-fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18-25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission-fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality.

  9. Mother–offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos

    Science.gov (United States)

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-01-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission–fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18–25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission–fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality. PMID:26045958

  10. The Effect of Kangaroo Mother Care Immediately after Delivery on Mother-infant Attachment 3 Months after Delivery

    Directory of Open Access Journals (Sweden)

    Fatemeh Zahra Karimi

    2016-09-01

    Full Text Available Background  The aim of this study was determine the effect of kangaroo mother care (KMC immediately after delivery on mother-infant attachment 3-month after delivery. Materials and Methods: In this RCT study, 72 mother-infant pairs were randomly divided in to kangaroo mother care and routine care groups.The intervention group received kangaroo mother care (KMC in the first two hours post birth. The control group just received routine hospital care. Mothers in the intervention group were encouraged to keep the baby in KMC as much as possible during the day and night throughout the neonatal period. Participants were followed up for three months after birth. The Main outcome measure was mother-infant attachment at 3 months postpartum and maternal anxiety about the baby at the same time. The data was collected by questionnaire (demographic information of parents and neonates and maternal attachment scale. Analysis was performed using SPSS software (version 14. Results: There was no significant difference between two groups regarding their baseline data. Mean maternal attachment score in the KMC group and in the routine care group at three months after delivery was 52.40±3.30 and 49.86±4.18 respectively, which was significantly higher in the KMC group (P

  11. Bringing compassion to the ethical dilemma in killing kangaroos for conservation: comment on "Conservation through sustainable use" by Rob Irvine.

    Science.gov (United States)

    Ramp, Daniel

    2013-06-01

    Ethical debate on the killing of kangaroos has polarised conservation and animal welfare science, yet at the heart of these scientific disciplines is the unifying aim of reducing harm to non-human animals. This aim provides the foundation for common ground, culminating in the development of compassionate conservation principles that seek to provide mechanisms for achieving both conservation and welfare goals. However, environmental decision-making is not devoid of human interests, and conservation strategies are commonly employed that suit entrenched positions and commercial gain, rather than valuing the needs of the non-human animals in need of protection. The case study on the wild kangaroo harvest presents just such a dilemma, whereby a conservation strategy is put forward that can only be rationalised by ignoring difficulties in the potential for realising conservation benefits and the considerable welfare cost to kangaroos. Rather than an open debate on the ethics of killing game over livestock, in this response I argue that efforts to bring transparency and objectivity to the public debate have to date been obfuscated by those seeking to maintain entrenched interests. Only by putting aside these interests will debate about the exploitation of wildlife result in humane, compassionate, and substantive conservation benefits.

  12. Familiarity breeds contempt: kangaroos persistently avoid areas with experimentally deployed dingo scents.

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    Michael H Parsons

    Full Text Available BACKGROUND: Whether or not animals habituate to repeated exposure to predator scents may depend upon whether there are predators associated with the cues. Understanding the contexts of habituation is theoretically important and has profound implication for the application of predator-based herbivore deterrents. We repeatedly exposed a mixed mob of macropod marsupials to olfactory scents (urine, feces from a sympatric predator (Canis lupus dingo, along with a control (water. If these predator cues were alarming, we expected that over time, some red kangaroos (Macropus rufous, western grey kangaroos (Macropus fuliginosus and agile wallabies (Macropus agilis would elect to not participate in cafeteria trials because the scents provided information about the riskiness of the area. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the effects of urine and feces independently and expected that urine would elicit a stronger reaction because it contains a broader class of infochemicals (pheromones, kairomones. Finally, we scored non-invasive indicators (flight and alarm stomps to determine whether fear or altered palatability was responsible for the response. Repeated exposure reduced macropodid foraging on food associated with 40 ml of dingo urine, X = 986.75+/-3.97 g food remained as compared to the tap water control, X = 209.0+/-107.0 g (P0.5. Macropodids did not habituate to repeated exposure to predator scents, rather they avoided the entire experimental area after 10 days of trials (R(2 = 83.8; P<0.001. CONCLUSIONS/SIGNIFICANCE: Responses to urine and feces were indistinguishable; both elicited fear-based responses and deterred foraging. Despite repeated exposure to predator-related cues in the absence of a predator, macropodids persistently avoided an area of highly palatable food. Area avoidance is consistent with that observed from other species following repeated anti-predator conditioning, However, this is the first time this response has been

  13. The application of a non-linear analysis technique to the monitoring of anesthetic effects in the rat

    NARCIS (Netherlands)

    Broek, P.L.C. van den; Egmond, J. van; Rijn, C.M. van; Dirksen, R.; Coenen, A.M.L.; Booij, L.H.D.J.

    2000-01-01

    To find a new measure from the EEG that quantifies the effects of anesthetics during surgery, the correlation dimension (CD) of the EEG of eight rats was estimated. To get informed about the anesthetic state, the noxious induced withdrawal reflex (NIWR) was measured, i.e. the force elicited by trans

  14. Characterization of intestinal absorption of C-glycoside flavonoid vicenin-2 from Lychnophora ericoides leafs in rats by nonlinear mixed effects modeling

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    Gabriela A. Buqui

    2015-06-01

    Full Text Available AbstractVicenin-2 (apigenin-6,8-di-C-β-d-glucopyranoside is present in hydroalcoholic extracts of the Brazilian species Lychnophora ericoides Mart., Asteraceae, leaves, and the biological effects of this compound have been demonstrated including anti-inflammatory, antioxidant and anti-tumor effects in rat models. Given the potential of this compound as a pharmacological agent, the aims of this investigation were to evaluate the extent of intestinal absorption of vicenin-2, and to determine the intestinal permeation profile using an in situ single-pass intestinal perfusion technique. A validated HPLC–UV method was applied to measure the amount of unabsorbed vicenin-2 in the gut after an oral administration of 180 mg kg-1 in five rats. A nonlinear mixed effects model was used to determine the absorption pharmacokinetic parameters assuming a first order absorption and active secretion processes for this compound, wherein the active secretion was characterized by a zero-order process. The population pharmacokinetic parameters obtained were 0.274 min-1 for the first-order absorption rate constant, 16.3% min-1 for the zero-order rate constant; the final percentage of the original dose that was absorbed in vivo was 40.2 ± 2.5%. These parameters indicated that vicenin-2 was rapidly absorbed in the small intestine. In contrast to literature information indicating no absorption of vicenin-2 in Caco-2 cells, our results suggested that vicenin-2 can be absorbed in the small intestine of rats. The finding supports further investigation of vicenin-2 as a viable oral phytopharmaceutical agent for digestive diseases.

  15. Single-strand conformation polymorphism analysis of genetic variation in Labiostrongylus longispicularis from kangaroos.

    Science.gov (United States)

    Huby-Chilton, F; Beveridge, I; Gasser, R B; Chilton, N B

    2001-06-01

    Single-strand conformation polymorphism (SSCP) analysis was employed to screen for sequence heterogeneity in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA of Labiostrongylus longispicularis, a parasitic strongylid nematode occuring in some species of kangaroo in different geographical regions of Australia. The results showed that most of the nematodes screened had different SSCP profiles, which were subsequently shown to correspond to polymorphisms and/or an indel in the ITS-2 sequence. These variable sites related mainly to unpaired regions of the predicted secondary structure of the precursor rRNA molecule. SSCP profiles could be used to distinguish L. longispicularis in Macropus robustus robustus (New South Wales) from L. longispicularis in Macropus robustus erubescens and Macropus rufus (South Australia). This difference corresponded to a transversional change in the ITS-2 sequence at alignment position 82. The study demonstrated clearly the effectiveness of SSCP analysis for future large-scale population genetic studies of L. longispicularis in order to test the hypothesis that L. longispicularis from different geographical regions represents multiple sibling species.

  16. Speed cameras, section control, and kangaroo jumps-a meta-analysis.

    Science.gov (United States)

    Høye, Alena

    2014-12-01

    A meta-analysis was conducted of the effects of speed cameras and section control (point-to-point speed cameras) on crashes. 63 effect estimates from 15 speed camera studies and five effect estimates from four section control studies were included in the analysis. Speed cameras were found to reduce total crash numbers by about 20%. The effect declines with increasing distance from the camera location. Fatal crashes were found to be reduced by 51%, this result may however be affected by regression to the mean (RTM). Section control was found to have a greater crash reducing effect than speed cameras (-30% for total crash numbers and -56% for KSI crashes). There is no indication that these results (except the one for the effect of speed cameras on fatal crashes) are affected by regression to the mean, publication bias or outlier bias. The results indicate that kangaroo driving (braking and accelerating) occurs, but no adverse effects on speed or crashes were found. Crash migration, i.e., an increase of crash numbers on other roads due to rerouting of traffic, may occur in some cases at speed cameras, but the results do not indicate that such effects are common. Both speed cameras and section control were found to achieve considerable speed reductions and the crash effects that were found in meta-analysis are of a similar size or greater than one might expect based on the effects on speed.

  17. Maternal singing during kangaroo care led to autonomic stability in preterm infants and reduced maternal anxiety.

    Science.gov (United States)

    Arnon, Shmuel; Diamant, Chagit; Bauer, Sofia; Regev, Rivka; Sirota, Gisela; Litmanovitz, Ita

    2014-10-01

    Kangaroo care (KC) and maternal singing benefit preterm infants, and we investigated whether combining these benefitted infants and mothers. A prospective randomised, within-subject, crossover, repeated-measures study design was used, with participants acting as their own controls. We evaluated the heart rate variability (HRV) of stable preterm infants receiving KC, with and without maternal singing. This included low frequency (LF), high frequency (HF) and the LF/HF ratio during baseline (10 min), singing or quiet phases (20 min) and recovery (10 min). Physiological parameters, maternal anxiety and the infants' behavioural state were measured. We included 86 stable preterm infants, with a postmenstrual age of 32-36 weeks. A significant change in LF and HF, and lower LF/HF ratio, was observed during KC with maternal singing during the intervention and recovery phases, compared with just KC and baseline (all p-values singing than just KC (p = 0.04). No differences in the infants' behavioural states or physiological parameters were found, with or without singing. Maternal singing during KC reduces maternal anxiety and leads to autonomic stability in stable preterm infants. This effect is not detected in behavioural state or physiological parameters commonly used to monitor preterm infants. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  18. The effect of formal, neonatal communication-intervention training on mothers in kangaroo care

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    Alta Kritzinger

    2014-01-01

    Full Text Available Background: Due to low-birth-weight, preterm birth, HIV and/or AIDS and poverty-related factors, South Africa presents with an increased prevalence of infants at risk of language delay. A Kangaroo Mother Care (KMC unit offers unique opportunities for training.Aim: The aim of the present study was to determine if formal, neonatal communication-intervention training had an effect on mothers’ knowledge and communication interaction with their high-risk infants.Methods: Three groups of mothers participated: Group 1 was trained whilst practicing KMC; Group 2 was not trained but practiced KMC; and Group 3 was also not trained but practiced sporadic KMC. Ten mothers per group were matched for age, education level and birth order of their infants. The individual training was based on graded sensory stimulation and responsive mother-infant communication interaction, which emphasised talking and singing by the mother.Results: Significant differences were found in mother-infant communication interaction between all three groups, which indicated a positive effect on Group 1 with training. Group 2, KMC without training, also had a positive effect on interaction. However, Group 1 mothers with training demonstrated better knowledge of their infants and were more responsive during interaction than the other two groups.Conclusion: The present study suggests that neonatal communication-intervention training adds value to a KMC programme. Normal 0 false false false EN-ZA X-NONE X-NONE

  19. The effect of kangaroo mother care on mental health of mothers with low birth weight infants

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    Zohreh Badiee

    2014-01-01

    Full Text Available Background: The mothers of premature infants are at risk of psychological stress because of separation from their infants. One of the methods influencing the maternal mental health in the postpartum period is kangaroo mother care (KMC. This study was conducted to evaluate the effect of KMC of low birth weight infants on their maternal mental health. Materials and Methods: The study was conducted in the Department of Pediatrics of Isfahan University of Medical Sciences, Isfahan, Iran. Premature infants were randomly allocated into two groups. The control group received standard caring in the incubator. In the experimental group, caring with three sessions of 60 min KMC daily for 1 week was practiced. Mental health scores of the mothers were evaluated by using the 28-item General Health Questionnaire. Statistical analysis was performed by the analysis of covariance using SPSS. Results: The scores of 50 infant-mother pairs were analyzed totally (25 in KMC group and 25 in standard care group. Results of covariance analysis showed the positive effects of KMC on the rate of maternal mental health scores. There were statistically significant differences between the mean scores of the experimental group and control subjects in the posttest period (P < 0.001. Conclusion: KMC for low birth weight infants is a safe way to improve maternal mental health. Therefore, it is suggested as a useful method that can be recommended for improving the mental health of mothers.

  20. Enhanced kangaroo mother care for heel lance in preterm neonates: a crossover trial.

    Science.gov (United States)

    Johnston, C C; Filion, F; Campbell-Yeo, M; Goulet, C; Bell, L; McNaughton, K; Byron, J

    2009-01-01

    To test if enhancing maternal skin-to-skin contact, or kangaroo mother care (KMC) by adding rocking, singing and sucking is more efficacious than simple KMC for procedural pain in preterm neonates. Preterm neonates (n=90) between 32 0/7 and 36 0/7 weeks' gestational age participated in a single-blind randomized crossover design. The infant was held in KMC with the addition of rocking, singing and sucking or the infant was held in KMC without additional stimulation. The Premature Infant Pain Profile was the primary outcome with time to recover as the secondary outcome. A repeated-measures analysis of covariance was employed for analyses. There were no significant differences in any of the 30 s time periods over the 2 min of blood sampling nor in time to return to baseline. Compared to historical controls of the same age in incubator, the pain scores were lower and comparable to other studies of KMC. There were site differences related to lower scores with the use of sucrose in one site and higher scores in younger, sicker infants in another site. The sensorial stimulations from skin-to-skin contact that include tactile, olfactory sensations from the mother are sufficient to decrease pain response in premature neonates. Other studies showing that rocking, sucking and music were efficacious were independent of skin-to-skin contact, which, when used alone has been shown to be effective as reported across studies.

  1. The Effect of Kangaroo Mother Care on Neonatal Outcomes in Iranian Hospitals: A Review

    Directory of Open Access Journals (Sweden)

    Leila Sarparast

    2015-01-01

    Full Text Available Context: Kangaroo Mother Care (KMC is a supportive technique that beings at the neonatal period and is one of the skin-to-skin contact methods of holding neonate by mother. This method has an important role in exclusive breastfeeding and thermal care of neonates. This study aimed to investigate the application of KMC and evaluate the effect of this technique in different neonatal outcomes, particularly in Iranian neonates. Moreover, this review can be a tool for formative evaluation for this newly introduced treatment intervention in Iran. Evidence Acquisition: This review was conducted in national and international databases concerning experience with KMC on term and preterm neonates admitted in Iranian hospitals from 2006 to 2014. The measured outcomes included physiologic, psychologic, and clinical effects of this practice on newborn infants. Results: In this study, 42 Persian and English language papers were reviewed and finally 26 articles were selected. Various effects of KMC on different factors such as analgesia; physiological effects, breastfeeding, icterus, length of hospitalization, infection, psychologic effects, and weight gain were found. Conclusions: The results showed that as a simple and suitable strategy for increasing the health status of the mothers and newborns, KMC had an important role in improvement of neonatal outcomes in neonatal wards of Iranian hospitals in recent ten years. Therefore, promoting this technique in all neonatal wards of the country can promote health status of this population.

  2. Rolling out of kangaroo mother care in secondary level facilities in Bihar-Some experiences

    Directory of Open Access Journals (Sweden)

    Sutapa B Neogi

    2016-01-01

    Full Text Available Background: Preterm birth is one of the leading causes of under-five child deaths worldwide and in India. Kangaroo mother care (KMC is a powerful and easy-to-use method to promote health and well-being and reduce morbidity and mortality in preterm/low birth weight (LBW babies. Objective: As the part of the roll-out of India Newborn Action Plan interventions, we implemented KMC in select facilities with an objective to assess the responsiveness of public health system to roll out KMC. Methods: KMC intervention was implemented in two select high priority districts, Gaya and Purnea in Bihar over the duration of 8 months from August 2015 to March 2016. The implementation of intervention was phased out into; situation analysis, implementation of intervention, and interim assessment. KMC model, as envisaged keeping in mind the building blocks of health system, was established in 6 identified health-care facilities. A pretested simple checklist was used to assess the awareness, knowledge, skills, and practice of KMC during baseline situational analysis and interim assessment phases for comparison. Results: The intervention clearly seemed to improve the awareness among auxiliary nurse midwives/nurses about KMC. Improvements were also observed in the availability of infrastructure required for KMC and support logistics like facility for manual expression of breast milk, cups/suitable devices such as paladi cups for feeding small babies and digital weighing scale. Although the recording of information regarding LBW babies and KMC practice improved, still there is scope for much improvement. Conclusion: There is a commitment at the national level to promote KMC in every facility. The present experience shows the possibility of rolling out KMC in secondary level facilities with support from government functionaries.

  3. Randomized controlled trial of music during kangaroo care on maternal state anxiety and preterm infants' responses.

    Science.gov (United States)

    Lai, Hui-Ling; Chen, Chia-Jung; Peng, Tai-Chu; Chang, Fwu-Mei; Hsieh, Mei-Lin; Huang, Hsiao-Yen; Chang, Shu-Chuan

    2006-02-01

    The purpose of this randomized controlled trial was to investigate the influences of music during kangaroo care (KC) on maternal anxiety and preterm infants' responses. There are no experimental studies that explore the influences of combination of music and KC on psychophysiological responses in mother-infant dyads. Purposive sampling was used to recruit 30 hospitalized preterm infants body weight 1500 gm and over, gestational age 37 weeks and lower from two NICUs. Mother-infant dyads were randomly assigned to the treatment and the control group using permuted block randomization stratified on gender. There were 15 mother-infant dyads in each group. Subjects in the treatment dyads listened to their choice of a lullaby music during KC for 60 min/section/day for three consecutive days. Control dyads received routine incubator care. Using a repeated measures design with a pretest and three posttests, the responses of treatment dyads including maternal anxiety and infants' physiologic responses (heart rate, respiratory rate, and O2 saturation) as well as behavioural state were measured. The results revealed that there were no significant differences between the two groups on infants' physiologic responses and the values were all in the normal range. However, infants in the treatment group had more occurrence of quiet sleep states and less crying (pMusic during KC also resulted in significantly lower maternal anxiety in the treatment group (peffect. The findings provide evidence for the use of music during KC as an empirically-based intervention for bahavioural state stability and maternal anxiety in mother-infant dyads.

  4. Supporting factors and barriers in implementing kangaroo mother care in Indonesia

    Directory of Open Access Journals (Sweden)

    Hadi Pratomo

    2012-01-01

    Full Text Available Background Kangaroo mother care (KMC was introduced to Indonesia in the 1990s. Since then, KMC has not been widely implemented and has not received national policy support. Objective The objectives of this case study were to implement KMC by an intervention that would ultimately benefit ten hospitals in Java, Indonesia, as well as identify supporting factors and barriers to KMC implementation. Methods An intervention with four phases was conducted in ten hospitals. Two teaching hospitals were supported to serve as training centers, six hospitals were supported to implement KMC and two other hospitals were supported to strengthen existing KMC practices. The four phases were comprised of a baseline assessment, a five-day training workshop, two supervisory visits to each hospital, and an end-line assessment. Results A total of 344 low birth weight infants received KMC during the intervention period. Good progress with regards to implementation was observed in most hospitals between the first and second supervisory visits. Supporting factors for KMC were the following: support received from hospital management, positive attitudes of healthcare providers, patients, families and communities, as well as the availability of resources. The most common challenges were record keeping and data collection, human resources and staff issues, infrastructure and budgets, discharge and follow-up, as well as family issues. Challenges related to the family were the inability of the mother or family to visit the infant frequently to provide KMC, and the affordability of hospital user fees for the infant to stay in the hospital for a sufficient period of time. Conclusion KMC appeared to be well accepted in most hospitals. For an intervention to have maximum impact, it is important to integrate services and maintain a complex network of communication systems. [Paediatr Indones. 2012;52:43-50].

  5. RAT非线性递归特征提取及故障检测中的应用%Nonlinear RAT Feature Extraction and Application in Fault Detection

    Institute of Scientific and Technical Information of China (English)

    赵竞雄; 王晓菊

    2014-01-01

    The average mutual information algorithm and false nearest neighbors algorithm were presented for calculating the optimal parameters of phase space reconstruction. On the basis of recurrence plot, the ratio of recurrence rate to the de-terminism which called RAT in this paper was proposed as a new nonlinear recurrence feature. And the algorithm of RAT was researched in detail. Three typical types of fault such as gas compressor fault, fuel apply fault and burning fault. Simu-lation result shows that the RAT feature can realize the fault diagnosis of engine effectively, and the fault diagnosis preci-sion can reach to 95.7%. According to the research result, it shows predominant performance and good engineering value in application.%提出使用平均互信息算法和虚假最近邻点算法提取非线性时间序列相空间重构的最优化重构参数。在研究递归图算法的基础上,提出使用递归图中的递归率与确定性的比值RAT作为一种新的非线性递归特征量,对其算法进行描述。对涡轮发动机涉及到气缸压缩、供油系统和燃烧室等涡轮机子系统3类典型故障进行了故障诊断实验。仿真实验结果表明,使用RAT特征能有效实现3类故障下的发动机故障的聚类和诊断,故障诊断准确率为95.7%,具有绝对优越的诊断性能,具有较强的工程实践意义。

  6. Discovering novel microRNAs and age-related nonlinear changes in rat brains using deep sequencing.

    Science.gov (United States)

    Yin, Lanxuan; Sun, Yubai; Wu, Jinfeng; Yan, Siyu; Deng, Zhenglu; Wang, Jun; Liao, Shenke; Yin, Dazhong; Li, Guolin

    2015-02-01

    Elucidating the molecular mechanisms of brain aging remains a significant challenge for biogerontologists. The discovery of gene regulation by microRNAs (miRNAs) has added a new dimension for examining this process; however, the full complement of miRNAs involved in brain aging is still not known. In this study, miRNA profiles of young, adult, and old rats were obtained to evaluate molecular changes during aging. High-throughput deep sequencing revealed 547 known and 171 candidate novel miRNAs that were differentially expressed among groups. Unexpectedly, miRNA expression did not decline progressively with advancing age; moreover, genes targeted by age-associated miRNAs were predicted to be involved in biological processes linked to aging and neurodegenerative diseases. These findings provide novel insight into the molecular mechanisms underlying brain aging and a resource for future studies on age-related brain disorders.

  7. Changing patterns of meat consumption and greenhouse gas emissions in Australia: Will kangaroo meat make a difference?

    Science.gov (United States)

    Ratnasiri, Shyama; Bandara, Jayatilleke

    2017-01-01

    The Australian per capita consumption of ruminant meat such as beef and lamb has declined over the last two decades. Over the same period, however, per capita consumption of non-ruminant meat such as chicken and pork has continued to increase. Furthermore, it is now observed that the human consumption of kangaroo meat is on the rise. This study investigates the implications of these changes in meat consumption patterns on Green House Gases (GHGs) emission mitigation in Australia using a Vector Auto Regression (VAR) forecasting approach. Our results suggest that the increase will continue in non-ruminant meat consumption and this will not only offset the decline in ruminant meat consumption, but will also raise the overall per capita meat consumption by approximately 1% annually. The per capita GHGs emissions will likely decrease by approximately 2.3% per annum, due to the inclusion of non-ruminant meat in Australian diets. The GHGs emissions can further be reduced if the average Australian consumer partially replaces ruminant meat with kangaroo meat.

  8. Changing patterns of meat consumption and greenhouse gas emissions in Australia: Will kangaroo meat make a difference?

    Science.gov (United States)

    Ratnasiri, Shyama; Bandara, Jayatilleke

    2017-01-01

    The Australian per capita consumption of ruminant meat such as beef and lamb has declined over the last two decades. Over the same period, however, per capita consumption of non-ruminant meat such as chicken and pork has continued to increase. Furthermore, it is now observed that the human consumption of kangaroo meat is on the rise. This study investigates the implications of these changes in meat consumption patterns on Green House Gases (GHGs) emission mitigation in Australia using a Vector Auto Regression (VAR) forecasting approach. Our results suggest that the increase will continue in non-ruminant meat consumption and this will not only offset the decline in ruminant meat consumption, but will also raise the overall per capita meat consumption by approximately 1% annually. The per capita GHGs emissions will likely decrease by approximately 2.3% per annum, due to the inclusion of non-ruminant meat in Australian diets. The GHGs emissions can further be reduced if the average Australian consumer partially replaces ruminant meat with kangaroo meat. PMID:28196141

  9. Aerobic characteristics of red kangaroo skeletal muscles: is a high aerobic capacity matched by muscle mitochondrial and capillary morphology as in placental mammals?

    Science.gov (United States)

    Dawson, Terence J; Mifsud, Brock; Raad, Matthew C; Webster, Koa N

    2004-07-01

    Marsupials and placentals together comprise the Theria, the advanced mammals, but they have had long independent evolutionary histories, with the last common ancestor occurring more than 125 million years ago. Although in the past the marsupials were considered to be metabolically 'primitive', the red kangaroo Macropus rufus has been reported to have an aerobic capacity (VO2max) comparable to that of the most 'athletic' of placentals such as dogs. However, kangaroos travel at moderate speeds with lower relative cost than quadrupedal placentals. Given the long independent evolution of the two therian groups, and their unusual locomotor energetics, do kangaroos achieve their high aerobic capacity using the same structural and functional mechanisms used by (athletic) placentals? Red kangaroo skeletal muscle morphometry matched closely the general aerobic characteristics of placental mammals. The relationship between total mitochondrial volume in skeletal muscle and VO2max during exercise was identical to that in quadrupedal placentals, and differed from that in bipedal humans. As for placentals generally, red kangaroo mitochondrial oxygen consumption at VO2max was 4.7 ml O2 min(-1) ml(-1) of mitochondria. Also, the inner mitochondrial membrane densities were 35.8 +/- 0.7 m2 ml(-1) of mitochondria, which is the same as for placental mammals, and the same pattern of similarity was seen for capillary densities and volumes. The overall data for kangaroos was equivalent to that seen in athletic placentals such as dogs and pronghorns. Total skeletal muscle mass was high, being around 50% of body mass, and was concentrated around the pelvis and lower back. The majority of the muscles sampled had relatively high mitochondrial volume densities, in the range 8.8-10.6% in the major locomotor muscles. Again, capillary densities and capillary blood volumes followed the pattern seen for mitochondria. Our results indicate that the red kangaroo, despite its locomotion and extreme

  10. Kangaroo mother care diminishes pain from heel lance in very preterm neonates: A crossover trial

    Directory of Open Access Journals (Sweden)

    McNaughton Kathryn

    2008-04-01

    Full Text Available Abstract Background Skin-to-skin contact, or kangaroo mother care (KMC has been shown to be efficacious in diminishing pain response to heel lance in full term and moderately preterm neonates. The purpose of this study was to determine if KMC would also be efficacious in very preterm neonates. Methods Preterm neonates (n = 61 between 28 0/7 and 31 6/7 weeks gestational age in three Level III NICU's in Canada comprised the sample. A single-blind randomized crossover design was employed. In the experimental condition, the infant was held in KMC for 15 minutes prior to and throughout heel lance procedure. In the control condition, the infant was in prone position swaddled in a blanket in the incubator. The primary outcome was the Premature Infant Pain Profile (PIPP, which is comprised of three facial actions, maximum heart rate, minimum oxygen saturation levels from baseline in 30-second blocks from heel lance. The secondary outcome was time to recover, defined as heart rate return to baseline. Continuous video, heart rate and oxygen saturation monitoring were recorded with event markers during the procedure and were subsequently analyzed. Repeated measures analysis-of-variance was employed to generate results. Results PIPP scores at 90 seconds post lance were significantly lower in the KMC condition (8.871 (95%CI 7.852–9.889 versus 10.677 (95%CI 9.563–11.792 p CI 103–142 versus 193 seconds (95%CI 158–227. Facial actions were highly significantly lower across all points in time reaching a two-fold difference by 120 seconds post-lance and heart rate was significantly lower across the first 90 seconds in the KMC condition. Conclusion Very preterm neonates appear to have endogenous mechanisms elicited through skin-to-skin maternal contact that decrease pain response, but not as powerfully as in older preterm neonates. The shorter recovery time in KMC is clinically important in helping maintain homeostasis. Trial Registration (Current

  11. Kangaroo mother care: a multi-country analysis of health system bottlenecks and potential solutions

    Science.gov (United States)

    2015-01-01

    Background Preterm birth is now the leading cause of under-five child deaths worldwide with one million direct deaths plus approximately another million where preterm is a risk factor for neonatal deaths due to other causes. There is strong evidence that kangaroo mother care (KMC) reduces mortality among babies with birth weight hospital discharge with follow-up. The World Health Organization has endorsed KMC for stabilised newborns in health facilities in both high-income and low-resource settings. The objectives of this paper are to: (1) use a 12-country analysis to explore health system bottlenecks affecting the scale-up of KMC; (2) propose solutions to the most significant bottlenecks; and (3) outline priority actions for scale-up. Methods The bottleneck analysis tool was applied in 12 countries in Africa and Asia as part of the Every Newborn Action Plan process. Country workshops involved technical experts to complete the survey tool, which is designed to synthesise and grade health system "bottlenecks", factors that hinder the scale-up, of maternal-newborn intervention packages. We used quantitative and qualitative methods to analyse the bottleneck data, combined with literature review, to present priority bottlenecks and actions relevant to different health system building blocks for KMC. Results Marked differences were found in the perceived severity of health system bottlenecks between Asian and African countries, with the former reporting more significant or very major bottlenecks for KMC with respect to all the health system building blocks. Community ownership and health financing bottlenecks were significant or very major bottlenecks for KMC in both low and high mortality contexts, particularly in South Asia. Significant bottlenecks were also reported for leadership and governance and health workforce building blocks. Conclusions There are at least a dozen countries worldwide with national KMC programmes, and we identify three pathways to scale: (1

  12. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  13. Nonlinear supratransmission

    Energy Technology Data Exchange (ETDEWEB)

    Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)

    2003-05-07

    A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.

  14. Marsupial and monotreme serum immunoglobulin binding by proteins A, G and L and anti-kangaroo antibody.

    Science.gov (United States)

    Vaz, Paola K; Hartley, Carol A; Browning, Glenn F; Devlin, Joanne M

    2015-12-01

    Serological studies are often conducted to examine exposure to infectious agents in wildlife populations. However, specific immunological reagents for wildlife species are seldom available and can limit the study of infectious diseases in these animals. This study examined the ability of four commercially available immunoglobulin-binding reagents to bind serum immunoglobulins from 17 species within the Marsupialia and Monotremata. Serum samples were assessed for binding, using immunoblots and ELISAs (Enzyme-linked immunosorbent assays), to three microbially-derived proteins - staphylococcal protein A, streptococcal protein G and peptostreptococcal protein L. Additionally, an anti-kangaroo antibody was included for comparison. The inter- and intra-familial binding patterns of the reagents to serum immunoglobulins varied and evolutionary distance between animal species was not an accurate predictor of the ability of reagents to bind immunoglobulins. Results from this study can be used to inform the selection of appropriate immunological reagents in future serological studies in these clades.

  15. A new species of Near-shore Marine Goby (Pisces: Gobiidae: Nesogobius) from Kangaroo Island, Australia.

    Science.gov (United States)

    Hammer, Michael P; Hoese, Douglass F; Bertozzi, Terry

    2015-12-11

    Nesogobius is one of two goby genera with all species wholly restricted to temperate Australian waters. Described here is a new member of the genus discovered during near-shore marine and estuarine fish sampling along the central southern Australian coastline. The tiger sandgoby Nesogobius tigrinus sp. nov. is distinguished from other congeners by a combination of colouration including four prominent vertical black bars on males; morphological characters involving body scales (large), head scales (naked), body depth (slender) and gill opening (wide); meristic counts including a lack of second dorsal and anal fin spines; and mitochondrial DNA sequence divergence. The species appears to be a narrow range endemic, restricted to specific sub-tidal habitat in the unique sheltered embayments of northeast Kangaroo Island. This study forms part of ongoing investigations to more fully describe the biodiversity and conservation requirements of the regional ichthyofauna.

  16. Genetic evaluation of the Association of Zoos and Aquariums Matschie's tree kangaroo (Dendrolagus matschiei) captive breeding program.

    Science.gov (United States)

    McGreevy, Thomas J; Dabek, Lisa; Husband, Thomas P

    2011-01-01

    Matschie's tree kangaroo (Dendrolagus matschiei) is an endangered species that has been bred in captivity since the 1970s. In 1992, the Tree Kangaroo Species Survival Plan(®) (TKSSP) was established to coordinate the captive management of Association of Zoos and Aquariums (AZA) D. matschiei. The TKSSP makes annual breeding recommendations primarily based on the mean kinship (MK) strategy. Captive breeding programs often use the MK strategy to preserve genetic diversity in small populations-to avoid the negative consequences of inbreeding and retain their adaptive potential. The ability of a captive breeding program to retain the population's genetic diversity over time can be evaluated by comparing the genetic diversity of the captive population to wild populations. We analyzed DNA extracted from blood and fecal samples from AZA (n = 71), captive (n = 28), and wild (n = 22) D. matschiei using eight microsatellite markers and sequenced the partial mitochondrial DNA control region gene. AZA D. matschiei had a similar expected heterozygosity (H(e) = 0.595 ± 0.184) compared with wild D. matschiei (H(e) = 0.628 ± 0.143), but they had different allelic frequencies (F(ST) = 0.126; P < 0.001). AZA D. matschiei haplotype diversity was almost two times lower than wild D. matschiei Ĥ = 0.740 ± 0.063. These data will assist management of AZA D. matschiei and serve as a baseline for AZA and wild D. matschiei genetic diversity values that could be used to monitor future changes in their genetic diversity. © 2010 Wiley Periodicals, Inc.

  17. Practical Nonlinearities

    Science.gov (United States)

    2016-07-01

    Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9

  18. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  19. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  20. Nonlinear analysis

    CERN Document Server

    Nanda, Sudarsan

    2013-01-01

    "Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.

  1. Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo.

    Directory of Open Access Journals (Sweden)

    Bo He

    Full Text Available Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos.

  2. Microstructural and compositional features of the fibrous and hyaline cartilage on the medial tibial plateau imply a unique role for the hopping locomotion of kangaroo.

    Science.gov (United States)

    He, Bo; Wu, Jian Ping; Xu, Jiake; Day, Robert E; Kirk, Thomas Brett

    2013-01-01

    Hopping provides efficient and energy saving locomotion for kangaroos, but it results in great forces in the knee joints. A previous study has suggested that a unique fibrous cartilage in the central region of the tibial cartilage could serve to decrease the peak stresses generated within kangaroo tibiofemoral joints. However, the influences of the microstructure, composition and mechanical properties of the central fibrous and peripheral hyaline cartilage on the function of the knee joints are still to be defined. The present study showed that the fibrous cartilage was thicker and had a lower chondrocyte density than the hyaline cartilage. Despite having a higher PG content in the middle and deep zones, the fibrous cartilage had an inferior compressive strength compared to the peripheral hyaline cartilage. The fibrous cartilage had a complex three dimensional collagen meshwork with collagen bundles parallel to the surface in the superficial zone, and with collagen bundles both parallel and perpendicular to the surface in the middle and deep zones. The collagen in the hyaline cartilage displayed a typical Benninghoff structure, with collagen fibres parallel to the surface in the superficial zone and collagen fibres perpendicular to the surface in the deep zone. Elastin fibres were found throughout the entire tissue depth of the fibrous cartilage and displayed a similar alignment to the adjacent collagen bundles. In comparison, the elastin fibres in the hyaline cartilage were confined within the superficial zone. This study examined for the first time the fibrillary structure, PG content and compressive properties of the central fibrous cartilage pad and peripheral hyaline cartilage within the kangaroo medial tibial plateau. It provided insights into the microstructure and composition of the fibrous and peripheral hyaline cartilage in relation to the unique mechanical properties of the tissues to provide for the normal activities of kangaroos.

  3. Rats

    Directory of Open Access Journals (Sweden)

    Alexey Kondrashov

    2012-01-01

    Full Text Available We aimed to perform a chemical analysis of both Alibernet red wine and an alcohol-free Alibernet red wine extract (AWE and to investigate the effects of AWE on nitric oxide and reactive oxygen species production as well as blood pressure development in normotensive Wistar Kyoto (WKY and spontaneously hypertensive rats (SHRs. Total antioxidant capacity together with total phenolic and selected mineral content was measured in wine and AWE. Young 6-week-old male WKY and SHR were treated with AWE (24,2 mg/kg/day for 3 weeks. Total NOS and SOD activities, eNOS and SOD1 protein expressions, and superoxide production were determined in the tissues. Both antioxidant capacity and phenolic content were significantly higher in AWE compared to wine. The AWE increased NOS activity in the left ventricle, aorta, and kidney of SHR, while it did not change NOS activity in WKY rats. Similarly, increased SOD activity in the plasma and left ventricle was observed in SHR only. There were no changes in eNOS and SOD1 expressions. In conclusion, phenolics and minerals included in AWE may contribute directly to increased NOS and SOD activities of SHR. Nevertheless, 3 weeks of AWE treatment failed to affect blood pressure of SHR.

  4. Método Mãe-Canguru Método Madre Canguro Kangaroo Mother Method

    Directory of Open Access Journals (Sweden)

    Roberta Costa

    2005-12-01

    conocimientos lo hace difícil, también, una adecuada evaluación de esta práctica con relación al recién-nacido y su familia pero, principalmente, en lo que concierne a la aplicación del MMC junto al equipo neonatal.Study of a qualitative nature, whose objective is to identify the knowledge that comes out produced and propagated in Brazilians and foreigners periodic, about Kangaroo Mother Method (KMM. An incursion for literature was carried through, from the databases Medline and Lilacs, as well as direct search to main the nursing periodic, during the period from 1995 through 2004. Eight five articles were selected, later catalogued and submitted to categorizes. After analysis of the articles, four categories were extracted on the thematic. The results had led to the conclusion that despite the KMM being configuring itself as a paradigmatic change in the care to the newborn, it does not have total correspondence with the theoretical production, taking the one that the practical one is developed, many times, without had theoretical sustentation. This gap of knowledge makes it difficult, also, one adequate evaluation of this practical with relation to newborn and its family but, mainly, in whom it says respect to the application of KMM together to the neonatal team.

  5. Nonlinear Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran

    2016-01-01

    We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.

  6. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  7. Scaling up kangaroo mother care in South Africa: 'on-site' versus 'off-site' educational facilitation

    Directory of Open Access Journals (Sweden)

    van Rooyen Elise

    2008-07-01

    Full Text Available Abstract Background Scaling up the implementation of new health care interventions can be challenging and demand intensive training or retraining of health workers. This paper reports on the results of testing the effectiveness of two different kinds of face-to-face facilitation used in conjunction with a well-designed educational package in the scaling up of kangaroo mother care. Methods Thirty-six hospitals in the Provinces of Gauteng and Mpumalanga in South Africa were targeted to implement kangaroo mother care and participated in the trial. The hospitals were paired with respect to their geographical location and annual number of births. One hospital in each pair was randomly allocated to receive either 'on-site' facilitation (Group A or 'off-site' facilitation (Group B. Hospitals in Group A received two on-site visits, whereas delegates from hospitals in Group B attended one off-site, 'hands-on' workshop at a training hospital. All hospitals were evaluated during a site visit six to eight months after attending an introductory workshop and were scored by means of an existing progress-monitoring tool with a scoring scale of 0–30. Successful implementation was regarded as demonstrating evidence of practice (score >10 during the site visit. Results There was no significant difference between the scores of Groups A and B (p = 0.633. Fifteen hospitals in Group A and 16 in Group B demonstrated evidence of practice. The median score for Group A was 16.52 (range 00.00–23.79 and that for Group B 14.76 (range 07.50–23.29. Conclusion A previous trial illustrated that the implementation of a new health care intervention could be scaled up by using a carefully designed educational package, combined with face-to-face facilitation by respected resource persons. This study demonstrated that the site of facilitation, either on site or at a centre of excellence, did not influence the ability of a hospital to implement KMC. The choice of outreach

  8. Nonlinear optimization

    CERN Document Server

    Ruszczynski, Andrzej

    2011-01-01

    Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t

  9. Evalvacija šolskega matematičnega tekmovanja Kenguru = Evaluation of the Kangaroo School Mathematical Competition

    Directory of Open Access Journals (Sweden)

    Barbara Komel

    2009-09-01

    Full Text Available Each year Slovene students of secondary vocational schools, among them also the Construction and Service School in Kranj (Economics and Service Educational Centre Kranj, compete in knowledge in the Kangaroo International Mathematical Competition . We decided to evaluate two points of view of the competition, namely processional in the sense of extra-curricular activities, i.e. preparation for the competition, and interpersonal in the sense of deepening the relations between teachers and students. One of the main aims of our evaluation, besides deepening the relations, was to motivate and prepare as many students as possible for the competition. While carrying out the project, there was a growing conviction that the process of evaluation is more important than its results, because it has united and brought closer all the participants, students as well as teacher-mentors. An extremely positive consequence of evaluation is the fact that the understanding of the competition itself has improved and it has also boosted its own efficiency. School climate has become friendlier, while the project group of mathematicians gained new guidelines for further work.

  10. Secretion of whey acidic protein and cystatin is down regulated at mid-lactation in the red kangaroo (Macropus rufus)

    Science.gov (United States)

    Nicholas, K.R.; Fisher, J.A.; Muths, E.; Trott, J.; Janssens, P.A.; Reich, C.; Shaw, D.C.

    2001-01-01

    Milk collected from the red kangaroo (Macropus rufus) between day 100 and 260 of lactation showed major changes in milk composition at around day 200 of lactation, the time at which the pouch young begins to temporarily exit the pouch and eat herbage. The carbohydrate content of milk declined abruptly at this time and although there was only a small increase in total protein content, SDS PAGE analysis of milk revealed asynchrony in the secretory pattern of individual proteins. The levels of ??-lactalbumin, ??-lactoglobulin, serum albumin and transferrin remain unchanged during lactation. In contrast, the protease inhibitor cystatin, and the putative protease inhibitor whey acidic protein (WAP) first appeared in milk at elevated concentrations after approximately 150 days of lactation and then ceased to be secreted at approximately 200 days. In addition, a major whey protein, late lactation protein, was first detected in milk around the time whey acidic protein and cystatin cease to be secreted and was present at least until day 260 of lactation. The co-ordinated, but asynchronous secretion of putative protease inhibitors in milk may have several roles during lactation including tissue remodelling in the mammary gland and protecting specific proteins in milk required for physiological development of the dependent young. ?? 2001 Elsevier Science Inc.

  11. Kangaroo care and behavioral and physiologic pain responses in very-low-birth-weight twins: a case study.

    Science.gov (United States)

    Cong, Xiaomei; Cusson, Regina M; Hussain, Naveed; Zhang, Di; Kelly, Sharon P

    2012-09-01

    The purpose of this case study was to describe pain responses in three study conditions: longer (30 minutes) kangaroo care (KC) before and throughout heel stick (KC30), shorter (15 minutes) KC before and throughout heel stick (KC15), and incubator care throughout heel stick (IC) in 28-week gestational age twins. Pain responses were measured by crying time, Preterm Infant Pain Profile (PIPP), and heart rate variability indexes, including low-frequency power (LF, representing sympathetic activity), high-frequency power (HF, parasympathetic activity), and LF/HF ratio (sympathetic-parasympathetic balance). Both twins cried more and had higher PIPP pain scores and tachycardia during heel stick in the IC condition. Infant B had an incident of apnea and tachycardia by the end of the heel stick and a bradycardia episode during recovery in the IC condition. The twins had lower LF/HF ratios (better autonomic nervous system balance) during recovery in both longer and shorter KC conditions compared with the IC condition. Infant B had difficulty returning to LF/HF ratio baseline level after the painful procedure in the IC condition. These data suggest that both longer and shorter KC before and throughout painful procedures can be helpful in reducing behavioral and physiologic pain responses in preterm infants.

  12. A new species of the basal "kangaroo" Balbaroo and a re-evaluation of stem macropodiform interrelationships.

    Directory of Open Access Journals (Sweden)

    Karen H Black

    Full Text Available Exceptionally well-preserved skulls and postcranial elements of a new species of the plesiomorphic stem macropodiform Balbaroo have been recovered from middle Miocene freshwater limestone deposits in the Riversleigh World Heritage Area of northwestern Queensland, Australia. This constitutes the richest intraspecific sample for any currently known basal "kangaroo", and, along with additional material referred to Balbaroo fangaroo, provides new insights into structural variability within the most prolific archaic macropodiform clade--Balbaridae. Qualitative and metric evaluations of taxonomic boundaries demonstrate that the previously distinct species Nambaroo bullockensis is a junior synonym of B. camfieldensis. Furthermore, coupled Maximum Parsimony and Bayesian phylogenetic analyses reveal that our new Balbaroo remains represent the most derived member of the Balbaroo lineage, and are closely related to the middle Miocene B. camfieldensis, which like most named balbarid species is identifiable only from isolated jaws. The postcranial elements of Balbaroo concur with earlier finds of the stratigraphically oldest balbarid skeleton, Nambaroo gillespieae, and suggest that quadrupedal progression was a primary gait mode as opposed to bipedal saltation. All Balbaroo spp. have low-crowned bilophodont molars, which are typical for browsing herbivores inhabiting the densely forested environments envisaged for middle Miocene northeastern Australia.

  13. Nonlinear channelizer

    Science.gov (United States)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  14. Nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)

    1989-01-01

    Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.

  15. Avaliação dos resultados neonatais do método canguru no Brasil Evaluation of the neonatal outcomes of the kangaroo mother method in Brazil

    Directory of Open Access Journals (Sweden)

    Fernando Lamy Filho

    2008-10-01

    Full Text Available OBJETIVO: Avaliar os resultados do método canguru no Brasil. MÉTODOS: Estudo de coorte prospectivo comparando 16 unidades que possuíam ou não a segunda fase do método canguru: oito eram centros nacionais de referência para o método canguru (grupo estudo, e oito faziam parte da Rede Brasileira de Pesquisas Neonatais (grupo controle. Foram incluídos 985 recém-nascidos pesando entre 500 e 1.749 g. Na análise multivariada, utilizou-se a regressão linear múltipla e a regressão de Poisson com ajuste robusto. RESULTADOS: Na análise ajustada (para peso de nascimento, idade gestacional, Score for Neonatal Acute Physiology Perinatal Extension II, Neonatal Therapeutic Intervention Scoring System, idade e escolaridade maternas, o tempo médio de internação (p = 0,14 e intercorrências clínicas na unidade intermediária ou canguru foram iguais entre os grupos. Peso (p = 0,012, comprimento (p = 0,039 e perímetro cefálico (p = 0,006 com 36 semanas de idade gestacional corrigida foram menores nas unidades canguru. As unidades canguru tiveram desempenho superior em relação ao aleitamento materno exclusivo na alta (69,2 versus 23,8%, p = 0,022. CONCLUSÃO: As evidências sugerem que a estratégia de humanização adotada pelo Ministério da Saúde é uma alternativa segura ao tratamento convencional e uma boa estratégia para a promoção do aleitamento materno.OBJECTIVE: To evaluate the results of the kangaroo mother method in Brazil. METHODS: A prospective cohort study comparing 16 units that have or do not have the second phase of the kangaroo mother method: eight were national centers of excellence for the kangaroo mother method (study group and eight were part of the Brazilian Neonatal Research Network (control group. A total of 985 newborn infants with birth weights of 500 to 1,749 g were enrolled. Multivariate analyses employed multiple linear regression and Poisson regression with robust adjustment. RESULTS: The adjusted analysis

  16. 健康和糖尿病大鼠红细胞荧光光谱非线性程度差异%Difference of Nonlinear Degree between Healthy and Diabetic Rat Erythocyte Fluorescence Spectrum

    Institute of Scientific and Technical Information of China (English)

    王磊; 刘贵栋; 刘丽; 刘玉婕; 娄宏君; 齐超; 肖洪彬; 迟文成

    2016-01-01

    Diabetes mellitus is one kind of chronic diseases which seriously threaten human health.It is very important to diag-nose in the early stage.With the development of diabetes,the structure and function of erythrocyte in the blood will change.So the peak position and peak height of erythrocyte fluorescence spectrum are different.These differences can be used to determine the status of diabetes.In the selection of the difference of spectral signal as the feature vector,the nonlinear degree of fluores-cence spectrum can be used as the feature vector.In order to describe the nonlinearity of the fluorescence spectrum signal,the nonlinear degree of the signal is described with the delay vector variance (DVV)method.By using the method of iterative ampli-tude adj usted Fourier transformation (IAAFT)to generate surrogate data of raw data,the nonlinear characteristic of the raw da-ta is determined by comparing the DVV of the original data and the surrogate data.The variance of the original data is the hori-zontal coordinates,and the variance of the surrogate data is the longitudinal coordinates,thus the DVV scatter plot is drawn. The DVV scatter plot of healthy rat erythrocyte fluorescence spectrum is almost coincident with its diagonal,which means the nonlinear degree of healthy rat erythrocyte fluorescence spectrum is lower.The DVV scatter plot of diabetic rat erythrocyte fluo-rescence spectrum deviates from its diagonal,which means the nonlinear degree of healthy rat erythrocyte fluorescence spectrum is higher,also the corresponding amino acid spectrum nonlinearity is deeper.Therefore,it is proposed that the nonlinear differ-ence between the healthy and diabetic fluorescence spectrum can be used as a feature of early diabetes diagnosis.%糖尿病是严重威胁人类健康的慢性疾病之一,对其进行早期诊断尤为重要。由于糖尿病病程的发展会对血液中红细胞的结构和功能产生影响,因此利用红细胞荧光光

  17. Comparative Effect of Massage Therapy versus Kangaroo Mother Care on Body Weight and Length of Hospital Stay in Low Birth Weight Preterm Infants.

    Science.gov (United States)

    Rangey, Priya Singh; Sheth, Megha

    2014-01-01

    Background. Massage therapy (MT) and kangaroo mother care (KMC) are both effective in increasing the weight and reducing length of hospital stay in low birth weight preterm infants but they have not been compared. Aim. Comparison of effectiveness of MT and KMC on body weight and length of hospital stay in low birth weight preterm (LBWPT) infants. Method. 30 LBWPT infants using convenience sampling from Neonatal Intensive Care Unit, V.S. hospital, were randomly divided into 2 equal groups. Group 1 received MT and Group 2 received KMC for 15 minutes, thrice daily for 5 days. Medically stable babies with gestational age Limitation. Long term follow-up was not taken.

  18. Trial gain of weight and hospital length stay of the low birth weight preterm infant in assistance for kangaroo mother care

    OpenAIRE

    Márcia Aparecida Giacomini Rodrigues; Maria Aparecida Tedeschi Cano

    2006-01-01

    The aim of this study was to evaluate if the Kangaroo Mother Care (KMC) interferes in the gain of weight and in the hospital length stay of the low birth weight preterm newborn (LWBPTN). For this, it was realized an analytic retrospective study, through the evaluation of the medical records of 60 LWBPTN with born weight less than 2000 g that received assistance by KMC, for a period of 2 hours per day and, 60 LWBPTN that received assistance by the Traditional Method of Care (TMC), admitted in ...

  19. Nonlinear Systems.

    Science.gov (United States)

    Seider, Warren D.; Ungar, Lyle H.

    1987-01-01

    Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…

  20. A sedge plant as the source of Kangaroo Island propolis rich in prenylated p-coumarate ester and stilbenes.

    Science.gov (United States)

    Duke, Colin C; Tran, Van H; Duke, Rujee K; Abu-Mellal, Abdallah; Plunkett, George T; King, Douglas I; Hamid, Kaiser; Wilson, Karen L; Barrett, Russell L; Bruhl, Jeremy J

    2017-02-01

    Propolis samples from Kangaroo Island, South Australia, were investigated for chemical constituents using high-field nuclear magnetic resonance spectral profiling. A type of propolis was found containing a high proportion of prenylated hydroxystilbenes. Subsequently, the botanical origin of this type of propolis was identified using a beehive propolis depletion method and analysis of flora. Ligurian honey bees, Apis mellifera ligustica Spinola, were found to produce propolis from resin exuded by the Australian native sedge plant Lepidosperma sp. Montebello (Cyperaceae). The plants, commonly known as sword sedge, were found to have resin that matched with the propolis samples identified as the most abundant propolis type on the island containing C- and O-prenylated tetrahydroxystilbenes (pTHOS) in addition to a small amount of prenylated p-coumarate. The isolation of five pTHOS not previously characterized are reported: (E)-4-(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene, (E)-2,4-bis(3-methyl-2-buten-1-yl)-3,3',4',5-tetrahydroxystilbene, (E)-2-(3-methyl-2-buten-1-yl)-3-(3-methyl-2-butenyloxy)-3',4',5-trihydroxystilbene, (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,3',5,5'-tetrahydroxystilbene and (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene. A National Cancer Institute 60 human cell line anticancer screen of three of these compounds showed growth inhibitory activity. The large Australasian genus Lepidosperma is identified as a valuable resource for the isolation of substances with medicinal potential. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Early kangaroo mother care vs. conventional method in stabilizing low birth weight infant: physiologic parameters (preliminary report

    Directory of Open Access Journals (Sweden)

    Rulina Suradi

    2006-12-01

    Full Text Available Background Kangaroo mother care (KMC has been accepted as an effective method in nursing low birth weight infant (LBWI. However, the application of this method in the early life of infants has not been studied in Indonesia. Objective To evaluate some physiologic parameters of LBWI treated with early KMC compared to conventional method. Methods This was a randomized clinical-trial, which compared early KMC to conventional method in stabilizing LBWI in the first 4 hours of life. All LBWI (birth weight 1500-2499 g bom at Cipto Mangunkusumo Hospital and Budi Kemuliaan Matemity Hospital Jakarta were recruited consecutively in the period of November 2001 until March 2002. The inclusion criteria were spontaneous delivery, APGAR scores 13t and 5th minute 37, and parental consent. Results Sixty-four subjects distributed evenly into early KMC group and control group. One subject in the KMC group and three subjects in the control group were excluded due to respiratory distress. The mean birth weight was 2091 (SO 299.4 g in the KMC group and 2184 (SO 214.9 g inthe control group. The mean gestational-age in both groups was 35.6 (SO 3.0 weeks. There were no statistical differences in mean temperature (P=0.281, heart rate (P=0.956, and respiratory rate (P=0.898 between the two groups during the first 4 hours of life. We found a larger proportion of infants reaching the temperature of 36.5QC in the KMC group, especially at one hour (49% vs. 7%; the difference of proportion was 0.42 (95%CI 0.22 to 0.61. Conclusion Early KMC method is proved to be as safe as conventional method in stabilizing healthy LBWI.

  2. Research Progress of Kangaroo Nursing Care Applied in Neonatal Pain Management%袋鼠式护理应用于新生儿疼痛管理的研究进展

    Institute of Scientific and Technical Information of China (English)

    肖苑红; 沈永珍; 黄晓睿

    2016-01-01

    袋鼠式护理已被广泛应用于新生儿护理中,在新生儿疼痛管理中的应用更受关注。本文通过综述袋鼠式护理应用于新生儿疼痛管理的应用机制、现状及效果,对今后开展袋鼠式护理应用于新生儿疼痛管理的研究提出建议。%Kangaroo care has been widely used in neonatal care,and more attention has been paid in the application of neonatal pain management. This article reviewed the mechanism of kangaroo care used in neonatal pain management,the current situation,and the effectiveness of kangaroo care used in neonatal pain management. Suggestions about how to apply kangaroo care in neonatal pain management were presented.

  3. Nonlinear PDEs

    OpenAIRE

    2015-01-01

    From the Back Cover: The emphasis throughout the present volume is on the practical application of theoretical mathematical models helping to unravel the underlying mechanisms involved in processes from mathematical physics and biosciences. It has been conceived as a unique collection of abstract methods dealing especially with nonlinear partial differential equations (either stationary or evolutionary) that are applied to understand concrete processes involving some important applications re...

  4. Kangaroo mother program: physical growth and morbidity in a cohort of children, followed from 40 weeks of postconceptional age until first year.

    Directory of Open Access Journals (Sweden)

    Diana Palencia

    2009-12-01

    Full Text Available Introduction: Up to 40 weeks of postconceptional age, the kangaroo mother program at the Hospital Universitario del Valle has proved to be a safe alternative for premature babies’ management with a low birth weight. Objectives: To evaluate the physical growth and morbidity in children followed since 40 weeks up to 1 year in the program. Material and methods: A cohort study was performed in newborn infants admitted to the kangaroo mother program in the newborn unit at the Hospital Universitario del Valle, Cali, Colombia, with birth weight lower than 2000 g, from 40 weeks postconceptional age up to one year age, between August 2002 and July 2006. Information was collected about maternal age and morbidity, prenatal control, type of birth, gender, birth weight, gestational age, breastfeeding, thick motor development, physical growth, morbidity, readmissions, mortality and tests results. Results: A total of 390 infants were admitted to the program, with a 61% of captation. 65% of theirs mothers did not have prenatal control. Before completing the 40 weeks, 5.3% were readmitted due to anaemia and apnoea. After 40 weeks, 13% were readmitted by bronchopneumonia and acute diarrhoea. Most of them were allocated in the reference percentiles for weight and size. Size had a better growth than weight. The cumulated low weight incidence for age at 13 months was 22%. Conclusions: To increase the coverage of prenatal control program and to watch that the children receive prescribed iron and formulated folic acid.

  5. A retrospective study of Babesia macropus associated with morbidity and mortality in eastern grey kangaroos (Macropus giganteus and agile wallabies (Macropus agilis

    Directory of Open Access Journals (Sweden)

    Shannon L. Donahoe

    2015-08-01

    Full Text Available This is a retrospective study of 38 cases of infection by Babesia macropus, associated with a syndrome of anaemia and debility in hand-reared or free-ranging juvenile eastern grey kangaroos (Macropus giganteus from coastal New South Wales and south-eastern Queensland between 1995 and 2013. Infection with B. macropus is recorded for the first time in agile wallabies (Macropus agilis from far north Queensland. Animals in which B. macropus infection was considered to be the primary cause of morbidity had marked anaemia, lethargy and neurological signs, and often died. In these cases, parasitised erythrocytes were few or undetectable in peripheral blood samples but were sequestered in large numbers within small vessels of visceral organs, particularly in the kidney and brain, associated with distinctive clusters of extraerythrocytic organisms. Initial identification of this piroplasm in peripheral blood smears and in tissue impression smears and histological sections was confirmed using transmission electron microscopy and molecular analysis. Samples of kidney, brain or blood were tested using PCR and DNA sequencing of the 18S ribosomal RNA and heat shock protein 70 gene using primers specific for piroplasms. The piroplasm detected in these samples had 100% sequence identity in the 18S rRNA region with the recently described Babesia macropus in two eastern grey kangaroos from New South Wales and Queensland, and a high degree of similarity to an unnamed Babesia sp. recently detected in three woylies (Bettongia penicillata ogilbyi in Western Australia.

  6. Thermal implications of interactions between insulation, solar reflectance, and fur structure in the summer coats of diverse species of kangaroo.

    Science.gov (United States)

    Dawson, Terence J; Maloney, Shane K

    2017-04-01

    Not all of the solar radiation that impinges on a mammalian coat is absorbed and converted into thermal energy at the coat surface. Some is reflected back to the environment, while another portion is reflected further into the coat where it is absorbed and manifested as heat at differing levels. Substantial insulation in a coat limits the thermal impact at the skin of solar radiation, irrespective where in the coat it is absorbed. In coats with low insulation, the zone where solar radiation is absorbed may govern the consequent heat load on the skin (HL-SR). Thin summer furs of four species of kangaroo from differing climatic zones were used to determine how variation in insulation and in coat spectral and structural characteristics influence the HL-SR. Coat depth, structure, and solar reflectance varied between body regions, as well as between species. The modulation of solar radiation and resultant heat flows in these coats were measured at low (1 m s(-1)) and high (6 m s(-1)) wind speeds by mounting them on a heat flux transducer/temperature-controlled plate apparatus in a wind tunnel. A lamp with a spectrum similar to solar radiation was used as a proxy for the sun. We established that coat insulation was largely determined by coat depth at natural fur lie, despite large variations in fibre density, fibre diameter, and fur mass. Higher wind speed decreased coat insulation, but depth still determined the overall level. A multiple regression analysis that included coat depth (insulation), fibre diameter, fibre density, and solar reflectance was used to determine the best predictors of HL-SR. Only depth and reflectance had significant impacts and both factors had negative weights, so, as either insulation or reflectance increased, HL-SR declined, the larger impact coming from coat reflectance. This reverses the pattern observed in deep coats where insulation dominates over effects of reflectance. Across all coats, as insulation declined, reflectance increased

  7. 袋鼠式护理对足月新生儿疼痛的护理效果%Kangaroo Care for Neonatal Pain Nursing Effect

    Institute of Scientific and Technical Information of China (English)

    宗小敏

    2013-01-01

    Objective To discuss kangaroo care for neonatal pain nursing effect, evaluation of its clinical application value. Methods From 2010 September to 2011 June in our hospital was born in 98 full-term neonates were divided randomly into two groups, the control group (n=49 ) using the routine nursing care, observation group (n=49 ) using a kangaroo care, two groups of neonatal pain, heart rate, oxygen saturation and crying time comparison. Results The observation group of neonatal pain score lower than those in the control group, the difference between the two groups was significant (P < 0.05 ); study group of neonatal heart rate lower than that of the control group, while the oxygen saturation is higher than that of control group, the difference between the two groups was statistically significant (P < 0.05 ); observation group of neonatal crying time shorter than the control group, the difference between the two groups was significant (P < 0.05 ). Conclusion Kangaroo care helps to reduce neonatal pain, promote stable vital signs, it is worth of application.%目的 讨论袋鼠式护理对于足月新生儿疼痛的护理效果,评价其临床应用价值.方法 将2010年9月-2011年6月在本院出生的98例足月新生儿随机分为两组,其中对照组(49例)采用常规护理方法,观察组(49例)采用袋鼠式护理,对两组新生儿的疼痛程度、心率、血氧饱和度及啼哭时间进行比较.结果 观察组新生儿疼痛评分低于对照组,两组差异具有统计学意义(P<0.05);观察组新生儿心率低于对照组,而血氧饱和度高于对照组,两组差异有统计学意义(P<0.05);观察组新生儿啼哭时间短于对照组,两组间差异具有统计学意义(P<0.05).结论袋鼠式护理有助于降低新生儿的疼痛感,促进生命体征稳定,临床应用效果好.

  8. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  9. Nonlinear Dynamics

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    3.1 A Unified Nonlinear Feedback Functional Method for Study Both Control and Synchronization of Spatiotemporal Chaos Fang Jinqing Ali M. K. (Department of Physics, The University of Lethbridge,Lethbridge, Alberta T1K 3M4,Canada) Two fundamental questions dominate future chaos control theories.The first is the problem of controlling hyperchaos in higher dimensional systems.The second question has yet to be addressed:the problem of controlling spatiotemporal chaos in a spatiotemporal system.In recent years, control and synchronization of spatiotemporal chaos and hyperchaos have became a much more important and challenging subject. The reason for this is the control and synchronism of such behaviours have extensive and great potential of interdisciplinary applications, such as security communication, information processing, medicine and so on. However, this subject is not much known and remains an outstanding open.

  10. Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride.

    Science.gov (United States)

    Kierdorf, Uwe; Death, Clare; Hufschmid, Jasmin; Witzel, Carsten; Kierdorf, Horst

    2016-01-01

    Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species.

  11. Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride

    Science.gov (United States)

    Kierdorf, Uwe; Death, Clare; Hufschmid, Jasmin; Witzel, Carsten; Kierdorf, Horst

    2016-01-01

    Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species. PMID:26895178

  12. Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus Exposed to High Environmental Levels of Fluoride.

    Directory of Open Access Journals (Sweden)

    Uwe Kierdorf

    Full Text Available Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species.

  13. Passage marker excretion in red kangaroo (Macropus rufus), collared peccary (Pecari tajacu) and colobine monkeys (Colobus angolensis, C. polykomos, Trachypithecus johnii).

    Science.gov (United States)

    Schwarm, Angela; Ortmann, Sylvia; Wolf, Christian; Streich, W Jürgen; Clauss, Marcus

    2009-11-01

    Ruminants are characterized by an efficient particle-sorting mechanism in the forestomach (FRST) followed by selective rechewing of large food particles. For the nonruminating foregut fermenter pygmy hippo it was demonstrated that large particles are excreted as fast as, or faster than, the small particles. The same has been suggested for other nonruminating foregut fermenters. We determined the mean retention time of fluids and different-sized particles in six red kangaroos (Macropus rufus), seven collared peccaries (Pecari tajacu) and three colobine monkeys (Colobus angolensis, C. polykomos, Trachypithecus johnii). We fed Co-EDTA as fluid and mordanted fiber as particle markers (Cr, Ce). Mean (+ or - SD) total tract retention time for fluids, small and large particles was 14 + or - 2, 29 + or - 10 and 30 + or - 9 hr in red kangaroos, 26 + or - 2, 34 + or - 5 and 32 + or - 3 hr in collared peccaries and 57 + or - 17, 55 + or - 19 and 54 + or - 19 hr in colobine monkeys, respectively. Large and small particles were excreted simultaneously in all species. There was no difference in the excretion of fluids and particles in the colobine monkeys, in contrast to the other foregut fermenters. In the nonprimate, nonruminant foregut fermenters, the difference in the excretion of fluids and small particles decreases with increasing food intake. On the contrary, ruminants keep this differential excretion constant at different intake levels. This may be a prerequisite for the sorting of particles in their FRST and enable them to achieve higher food intake rates. The functional significance of differential excretion of fluids and particles from the FRST requires further investigations.

  14. THE EFFECTIVENESS OF COMBINATION OF KANGAROO MOTHER CARE METHOD AND LULLABY MUSIC THERAPY ON VITAL SIGN CHANGE IN INFANTS WITH LOW BIRTH WEIGHT

    Directory of Open Access Journals (Sweden)

    Nuuva Yusuf

    2017-08-01

    Full Text Available Background: Kangaroo mother care (KMC and lullaby music methods have been considered as the alternative treatment for vital sign changes in low birth weight infants. However, little is known about the combination of the two methods. Objective: To identify effectiveness of combinations of Kangaroo mother care and Lullaby music methods on changes in vital signs in low birth weight infants. Methods: A quasi experiment with non-equivalent control group design. This study was conducted on October– December 2016 at the General Hospital of Ambarawa and General Hospital of Ungaran, Semarang. There were 36 samples selected using consecutive sampling divided into three groups, namely: 1 a group of LBW infants with the combination of KMC and lullaby music, 2 a LBW infant group with the lullaby music intervention, and 3 a control group given standard care in LBW infants by KMC method. Paired t-test and MANOVA test were used to analyzed the data. Results: Findings revealed that there were significant differences between the combination group, lullaby music group, and control group in temperature (p=0.003, pulse (p=0.001, respiration (p=0.001, and oxygen saturation (p=0.014 with significant value of <0.05, which indicated that there was a statistically significant difference in vital sign changes among the three groups. Conclusion: The combination of KMC method and Lullaby music intervention was effective on vital sign changes (temperature, pulse, respiration, and oxygen saturation compared with the lullaby music group alone and control group with KMC method in low birth weight infants. It is suggested that the combination of KMC and Lullaby music methods can be used as an alternative to improve LBW care for mothers in the NICU and at home and to reach the stability of the baby's vital signs.

  15. Nonlinear Materials Characterization Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Nonlinear Materials Characterization Facility conducts photophysical research and development of nonlinear materials operating in the visible spectrum to protect...

  16. Nonlinear singular vectors and nonlinear singular values

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel concept of nonlinear singular vector and nonlinear singular value is introduced, which is a natural generalization of the classical linear singular vector and linear singular value to the nonlinear category. The optimization problem related to the determination of nonlinear singular vectors and singular values is formulated. The general idea of this approach is demonstrated by a simple two-dimensional quasigeostrophic model in the atmospheric and oceanic sciences. The advantage and its applications of the new method to the predictability, ensemble forecast and finite-time nonlinear instability are discussed. This paper makes a necessary preparation for further theoretical and numerical investigations.

  17. Changes in electroencephalogram in rat epilepsy model via nonlinear dynamical approach%应用非线性动力学指标分析大鼠癫痫模型脑电信息变化

    Institute of Scientific and Technical Information of China (English)

    许敏光; 夏鹏; 蒋勇; 龙开平; 杨继庆

    2005-01-01

    BACKGROUND: The dynamic characteristics of electroencephalogram (EEG) include a decrease in the chaotic dimension, the correlation dimen sion, the Lyapunov exponent, the chaotic complexity, the freedom of EEG and an enhanced synchronization and periodicity of the EEG from several minutes to tens of minutes before epileptic seizures. All these characteristics prefigure the forthcoming seizures. Some studies have proven that the non linear dynamical system can be used as a feasible approach to explore the potential variables for describing the chaos portrait of EEG. OBJECTIVE: To analyze the electric characteristics of EEG signal in the epileptic seizures in rat model by investigating the nonlinear dynamical variables, such as the approximate entropy (ApEn) and correlation dimen sion. DESIGN: Observational and experimental study based on animals. SETTING: Department of Medical Engineering, Department of Gastroen terology, Second Artilleryman General Hospital of Chinese PLA; Department of Physics, Faulty of Biomedical Engineering, Fourth Military Medical Uni versity of Chinese PLA. MATERIALS: From September 2001 to January 2002, this study was conducted at the Complexity Laboratory of the Biomedical Department of the Fourth Military Medical University of Chinese PLA. Six male SD rats,weighing 150- 200 g, were selected.INTERVENTIONS: After intraperitoneal injection of chloral hydrate (0. 5 mL), the male SD rats were deeply anesthetized. When their EEG signal became stable, bemegride injection was diluted at 1:1 with saline and was given on a volume of 0.5 mL to the rats intraperitoneally. After a while,the epileptic seizures started marked by a spasm with a deep roar. The entire epileptic seizures were recorded. According to the shape of EEG waves and the corresponding symptoms of the rats during their seizures, data of the four phases, referring to normal condition, preictal phase, ictal phase and postictal phases of epileptic seizures, were selected for nonlinear

  18. NONLINEAR EXPECTATIONS AND NONLINEAR MARKOV CHAINS

    Institute of Scientific and Technical Information of China (English)

    PENG SHIGE

    2005-01-01

    This paper deals with nonlinear expectations. The author obtains a nonlinear generalization of the well-known Kolmogorov's consistent theorem and then use it to construct filtration-consistent nonlinear expectations via nonlinear Markov chains. Compared to the author's previous results, i.e., the theory of g-expectations introduced via BSDE on a probability space, the present framework is not based on a given probability measure. Many fully nonlinear and singular situations are covered. The induced topology is a natural generalization of Lp-norms and L∞-norm in linear situations.The author also obtains the existence and uniqueness result of BSDE under this new framework and develops a nonlinear type of von Neumann-Morgenstern representation theorem to utilities and present dynamic risk measures.

  19. 袋鼠式护理对足月新生儿疼痛的护理效果%Kangaroo Care for Nursing Effect of Neonatal Pain

    Institute of Scientific and Technical Information of China (English)

    游李平

    2013-01-01

      目的:探究袋鼠式护理对足月新生儿疼痛的护理效果及其临床意义。方法:将本院2012年10月-2013年2月内足月出生的58例新生儿随机平均分为两组,各29例。研究组采用袋鼠式护理,对照组采用常规护理,比较两组新生儿疼痛程度、心率和血氧饱和度方面的差异。结果:在疼痛程度和心率方面,研究组明显低于对照组比较,差异具有统计学意义(P<0.05);在血氧饱和度方面,研究组明显高于对照组,比较差异具有统计学意义(P<0.05)。结论:袋鼠式护理对比较于足月新生儿疼痛的护理效果显著,能够有效降低足月新生儿的疼痛感,对于新生儿的心理和生理均有良好的促进作用。%Objective:To explore the kangaroo care for nursing effect of neonatal pain and its clinical significance. Method:In our hospital from 2012 October to 2013 February 58 cases of newborn infants born at term were randomly divided into two groups,each of 29 cases. Study group received kangaroo care,and the control group received routine nursing care.To compare the differences in neonatal pain,heart rate and blood oxygen saturation between the two groups. Result:The degree of pain and heart rate of the study group was significantly lower than that of the control group,the difference was statistically significant(P<0.05);in the blood oxygen saturation of the study group was significantly higher than that of the control group,with statistically significant differences(P<0.05). Conclusion:Kangaroo care for nursing effect of neonatal pain significantly,can effectively reduce the full-term newborn pain,to promote the role of newborn’s psychological and physical have good. As a kind of high quality nursing methods,get recognition and promotion in clinic.

  20. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  1. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    The purpose of the research presented here is to investigate basic physical properties in nonlinear optical materials with delayed or nonlocal nonlinearity. Soliton propagation, spectral broadening and the influence of the nonlocality or delay of the nonlinearity are the main focusses in the work...

  2. Noncommutative Nonlinear Supersymmetry

    CERN Document Server

    Nishino, H; Nishino, Hitoshi; Rajpoot, Subhash

    2002-01-01

    We present noncommutative nonlinear supersymmetric theories. The first example is a non-polynomial Akulov-Volkov-type lagrangian with noncommutative nonlinear global supersymmetry in arbitrary space-time dimensions. The second example is the generalization of this lagrangian to Dirac-Born-Infeld lagrangian with nonlinear supersymmetry realized in dimensions D=2,3,4 and 6 (mod 8).

  3. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind P. Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications,the Raman amplification being only one of the recent examples. In this tutorial I review the vario us nonlinear effects occurring in optical fibers from both standpoints..

  4. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind; P.; Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications, the Raman amplification being only one of the recent examples. In this tutorial I review the various nonlinear effects occurring in optical fibers from both standpoints..

  5. PBH tests for nonlinear systems

    NARCIS (Netherlands)

    Kawano, Yu; Ohtsuka, Toshiyuki

    2017-01-01

    Recently, concepts of nonlinear eigenvalues and eigenvectors are introduced. In this paper, we establish connections between the nonlinear eigenvalues and nonlinear accessibility/observability. In particular, we provide a generalization of Popov- Belevitch-Hautus (PBH) test to nonlinear accessibilit

  6. Effect of kangaroo mother care on growth and development of low birthweight babies up to 12 months of age: a controlled clinical trial.

    Science.gov (United States)

    Bera, Alpanamayi; Ghosh, Jagabandhu; Singh, Arun K; Hazra, Avijit; Mukherjee, Suchandra; Mukherjee, Ranajit

    2014-06-01

    Kangaroo mother care (KMC) is a nonconventional low-cost method of newborn care. Our aim was to assess the effect of sustained KMC on the growth and development of low birthweight Indian babies up to the age of 12 months. We enrolled 500 mother and baby pairs, in groups of five, in a parallel group controlled clinical trial. The three infants with the lowest birthweight in each group received KMC, while the other two received conventional care. All babies were exclusively breastfed for 6 months. Babies in the intervention group were provided KMC until the infant was 40 weeks of corrected gestation or weighed 2500 g. Weight, length and head, chest and arm circumferences were evaluated at birth and at the corrected ages of 0, 3, 6, 9 and 12 months. Development was assessed using the Developmental Assessment Scales for Indian Infants (DASII) at 12 months. The KMC babies rapidly achieved physical growth parameters similar to the control babies at 40 weeks of corrected age. But after that, they surpassed them, despite being smaller at birth. DASII motor and mental development quotients were also significantly better for KMC babies. The infants in the KMC group showed better physical growth and development than the conventional control group. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  7. The impact of the method Kangaroo Mother Care in the learning process of low-birth-weight preterm infants: A literature review

    Directory of Open Access Journals (Sweden)

    Mariana de Paiva Franco

    2014-04-01

    Full Text Available Technology advances and scientific studies in Neonatal Intensive Care Units (NICU have contributed significantly to reduce mortality and morbidity of at-risk newborns (NB. However, they are more likely to present neurological and/or developmental psychomotor delay with neurological and sensory alterations. Therefore, proposals for neonatal intervention were developed with the aim of protecting the baby and offering appropriate incentives to minimize the effects of hospital intervention. To this end, programs of protective measures such as the Kangaroo Mother Care (KMC were developed. Given the relevance of the issue described, this systematic review critically appraises articles from the national and international literature, published in recent years (from 2000 to 2011, that describe whether the KMC can be a protective factor for the development of writing in premature infants. The textual search was conducted using the Virtual Health Library (VHL, a website that covers publications worldwide, allowing access to articles from health science, including LILACS, IBECS, MEDLINE, Cochrane Library and SciELO, as database. The findings revealed that infants who participated in the KMC program showed improvements in their development and that factors such as low-birth-weight prematurity and learning disorders have close relationship with the onset of motor impairments and changes in psychomotor development. The findings showed no articles describing the KMC as a protective factor for the incidence of dysgraphia. Thus, we emphasize the importance of conducting further studies on these topics.

  8. Comparative Effect of Massage Therapy versus Kangaroo Mother Care on Body Weight and Length of Hospital Stay in Low Birth Weight Preterm Infants

    Directory of Open Access Journals (Sweden)

    Priya Singh Rangey

    2014-01-01

    Full Text Available Background. Massage therapy (MT and kangaroo mother care (KMC are both effective in increasing the weight and reducing length of hospital stay in low birth weight preterm infants but they have not been compared. Aim. Comparison of effectiveness of MT and KMC on body weight and length of hospital stay in low birth weight preterm (LBWPT infants. Method. 30 LBWPT infants using convenience sampling from Neonatal Intensive Care Unit, V.S. hospital, were randomly divided into 2 equal groups. Group 1 received MT and Group 2 received KMC for 15 minutes, thrice daily for 5 days. Medically stable babies with gestational age < 37 weeks and birth weight < 2500 g were included. Those on ventilators and with congenital, orthopedic, or genetic abnormality were excluded. Outcome measures, body weight and length of hospital stay, were taken before intervention day 1 and after intervention day 5. Level of significance was 5%. Result. Data was analyzed using SPSS16. Both MT and KMC were found to be effective in improving body weight (P = 0.001, P = 0.001. Both were found to be equally effective for improving body weight (P = 0.328 and reducing length of hospital stay (P = 0.868. Conclusion. MT and KMC were found to be equally effective in improving body weight and reducing length of hospital stay. Limitation. Long term follow-up was not taken.

  9. Nonlinear dynamics and complexity

    CERN Document Server

    Luo, Albert; Fu, Xilin

    2014-01-01

    This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.

  10. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    Antonella Fiacca; Nikolaos Matzakos; Nikolaos S Papageorgiou; Raffaella Servadei

    2001-11-01

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all $\\mathbb{R}$. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of $\\mathbb{R}$. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).

  11. Simulation of Vegetation Recovery from Military Disturbances on Fort Bliss

    Science.gov (United States)

    2005-11-01

    distinguished: Pinyon juniper, Mesa grassland, Black grama grasslands, Whitethorn acacia , Creosotebush, Sandsage, and Mes- quite (Pidgeon 2000). However, a GIS...Granivory Insects Rodents kangaroo rats Ants IV.5. Digging Rodents kangaroo rats Lagomorphs IV.6. Extreme events Drought

  12. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  13. Nonlinear Cross Gramians

    Science.gov (United States)

    Ionescu, Tudor C.; Scherpen, Jacquelien M. A.

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain linearization results that correspond to the notion of a cross Gramian for symmetric linear systems. Furthermore, first steps towards relations with the singular value functions of the nonlinear Hankel operator are studied and yield promising results.

  14. Nonlinear functional analysis

    Directory of Open Access Journals (Sweden)

    W. L. Fouché

    1983-03-01

    Full Text Available In this article we discuss some aspects of nonlinear functional analysis. It included reviews of Banach’s contraction theorem, Schauder’s fixed point theorem, globalising techniques and applications of homotopy theory to nonlinear functional analysis. The author emphasises that fundamentally new ideas are required in order to achieve a better understanding of phenomena which contain both nonlinear and definite infinite dimensional features.

  15. Nonlinear Electrodynamics and QED

    OpenAIRE

    2003-01-01

    The limits of linear electrodynamics are reviewed, and possible directions of nonlinear extension are explored. The central theme is that the qualitative character of the empirical successes of quantum electrodynamics must be used as a guide for understanding the nature of the nonlinearity of electrodynamics at the subatomic level. Some established theories of nonlinear electrodynamics, namely, those of Mie, Born, and Infeld are presented in the language of the modern geometrical and topologi...

  16. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  17. Nonlinear magnetic metamaterials.

    Science.gov (United States)

    Shadrivov, Ilya V; Kozyrev, Alexander B; van der Weide, Daniel W; Kivshar, Yuri S

    2008-12-08

    We study experimentally nonlinear tunable magnetic metamaterials operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We demonstrate that at higher powers the transmission of the metamaterial becomes power-dependent and, as a result, such metamaterial can demonstrate various nonlinear properties. In particular, we study experimentally the power-dependent shift of the transmission band and demonstrate nonlinearity-induced enhancement (or suppression) of wave transmission. (c) 2008 Optical Society of America

  18. Organic nonlinear optical materials

    Science.gov (United States)

    Umegaki, S.

    1987-01-01

    Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.

  19. Nonlinearity-reduced interferometer

    Science.gov (United States)

    Wu, Chien-ming

    2007-12-01

    Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.

  20. Trial gain of weight and hospital length stay of the low birth weight preterm infant in assistance for kangaroo mother care

    Directory of Open Access Journals (Sweden)

    Márcia Aparecida Giacomini Rodrigues

    2006-08-01

    Full Text Available The aim of this study was to evaluate if the Kangaroo Mother Care (KMC interferes in the gain of weight and in the hospital length stay of the low birth weight preterm newborn (LWBPTN. For this, it was realized an analytic retrospective study, through the evaluation of the medical records of 60 LWBPTN with born weight less than 2000 g that received assistance by KMC, for a period of 2 hours per day and, 60 LWBPTN that received assistance by the Traditional Method of Care (TMC, admitted in the unity of neonatal intensive care and unity of premature of a private maternity in the city of Ribeirão Preto-SP, Brazil, comparing the gain of weight and the hospital length stay. We did not find differences statistically significant in relation to the gain of weight of the LWBPTN assisted by KMC, in relation to LWBPTN assisted by the TMC, 15,8 and 14,9 g/per day, respectively. In relation to the time of admission, we also did not find differences statistically significant, 27,3 and 26,2 days, for the LWBPTN in the KMC and TMC, respectively, although in the stratification of the sample, the LBWPTN with pregnancy age < 30 weeks or birth weight < 1500 g left the hospital 3 days earlier in the KMC. It was concluded that the KMC, in the conditions of this study, it seems not to interfere significatively in the gain of weight and in the time of admission of LWBPTN. We emphasize that the utilization of KMC in the assistance to the LWBPTN of low weight is a viable model, even for the private health institution.

  1. Kangaroo mother method: randomised controlled trial of an alternative method of care for stabilised low-birthweight infants. Maternidad Isidro Ayora Study Team.

    Science.gov (United States)

    Sloan, N L; Camacho, L W; Rojas, E P; Stern, C

    1994-09-17

    Because resources for care of low-birthweight (LBW) infants in developing countries are scarce, the Kangaroo mother method (KMM) was developed. The infant is kept upright in skin-to-skin contact with the mother's breast. Previous studies reported several benefits with the KMM but interpretation of their findings is limited by small size and design weaknesses. We have done a longitudinal, randomised, controlled trial at the Isidro Ayora Maternity Hospital in Quito, Ecuador. Infants with LBW (< 2000 g) who satisfied out-of-risk criteria of tolerance of food and weight stabilisation were randomly assigned to KMM and control (standard incubator care) groups (n = 128 and 147, respectively). During 6 months of follow-up the KMM group had a significantly lower rate than the control group of serious illness (lower-respiratory-tract disorders, apnoea, aspiration, pneumonia, septicaemia, general infections; 7 [5%] vs 27 [18%], p < 0.002), although differences between the groups in less severe morbidity were not significant. There was no significant difference in growth or in the proportion of women breastfeeding, perhaps because the proportion breastfeeding was high in both groups owing to strong promotion. Mortality was the same in both groups; most deaths occurred during the stabilisation period before randomisation. KMM mothers made more unscheduled clinic visits than control mothers but their infants had fewer re-admissions and so the cost of care was lower with the KMM. Since the eligibility criteria excluded nearly 50% of LBW infants from the study, the KMM is not universally applicable to these infants. The benefits might be greater in populations where breastfeeding is not so common.

  2. Lasers for nonlinear microscopy.

    Science.gov (United States)

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  3. Nonlinear optical materials.

    Science.gov (United States)

    Eaton, D F

    1991-07-19

    The current state of materials development in nonlinear optics is summarized, and the promise of these materials is critically evaluated. Properties and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.

  4. Estimating nonlinear models

    Science.gov (United States)

    Billings, S. A.

    1988-03-01

    Time and frequency domain identification methods for nonlinear systems are reviewed. Parametric methods, prediction error methods, structure detection, model validation, and experiment design are discussed. Identification of a liquid level system, a heat exchanger, and a turbocharge automotive diesel engine are illustrated. Rational models are introduced. Spectral analysis for nonlinear systems is treated. Recursive estimation is mentioned.

  5. Nonlinear Cross Gramians

    NARCIS (Netherlands)

    Ionescu, T. C.; Scherpen, J. M. A.; Korytowski, A; Malanowski, K; Mitkowski, W; Szymkat, M

    2009-01-01

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain

  6. Engineered nonlinear lattices

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.

    1999-01-01

    We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...

  7. Controllability in nonlinear systems

    Science.gov (United States)

    Hirschorn, R. M.

    1975-01-01

    An explicit expression for the reachable set is obtained for a class of nonlinear systems. This class is described by a chain condition on the Lie algebra of vector fields associated with each nonlinear system. These ideas are used to obtain a generalization of a controllability result for linear systems in the case where multiplicative controls are present.

  8. Nonlinear Maneuver Autopilot

    Science.gov (United States)

    Menon, P. K. A.; Badgett, M. E.; Walker, R. A.

    1992-01-01

    Trajectory-control laws based on singular-perturbation theory and nonlinear dynamical modeling. Nonlinear maneuver autopilot commands flight-test trajectories of F-15 airplane. Underlying theory of controller enables separation of variables processed in fast and slow control loops, reducing amount of computation required.

  9. Nonlinear optics and photonics

    CERN Document Server

    He, Guang S

    2015-01-01

    This book provides a comprehensive presentation on most of the major topics in nonlinear optics and photonics, with equal emphasis on principles, experiments, techniques, and applications. It covers many major new topics including optical solitons, multi-photon effects, nonlinear photoelectric effects, fast and slow light , and Terahertz photonics. Chapters 1-10 present the fundamentals of modern nonlinear optics, and could be used as a textbook with problems provided at the end of each chapter. Chapters 11-17 cover the more advanced topics of techniques and applications of nonlinear optics and photonics, serving as a highly informative reference for researchers and experts working in related areas. There are also 16 pages of color photographs to illustrate the visual appearances of some typical nonlinear optical effects and phenomena. The book could be adopted as a textbook for both undergraduates and graduate students, and serve as a useful reference work for researchers and experts in the fields of physics...

  10. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  11. Efeitos do Método Mãe Canguru nos sinais vitais de recém-nascidos pré-termo de baixo peso Effects of Kangaroo Mother Care on the vital signs of low-weight preterm newborns

    Directory of Open Access Journals (Sweden)

    CM Almeida

    2007-02-01

    Full Text Available OBJETIVO: Avaliar as freqüências cardíaca e respiratória, a pressão arterial média, a temperatura e a saturação periférica de oxigênio dos recém-nascidos pré-termo (RNPT de baixo peso, antes e após a aplicação do MMC. MÉTODOS: Foram avaliados 22 RNPT de baixo peso, saudáveis, de ambos os sexos, não portadores de deficiências neurológicas, cardíacas e/ou respiratórias. A avaliação foi realizada após trinta minutos de permanência do RNPT em berço comum e após trinta minutos de aplicação do MMC, por 3 dias consecutivos. Para a avaliação, foram utilizados monitor cardíaco com dispositivo para medida da pressão arterial média de forma não invasiva e sensor para a oximetria de pulso, termômetro e cronômetro. RESULTADOS: Os resultados não mostraram alterações significativas quanto à pressão arterial média (p> 0,05 e freqüência cardíaca (p> 0,05 após a aplicação do MMC, mas, por outro lado, houve aumento significativo da temperatura axilar (pOBJECTIVE: The aim of this study was to evaluate the heart and respiration rates, mean arterial pressure, temperature and peripheral oxygen saturation of low-weight preterm newborns, before and after the application of kangaroo mother care. METHOD: Twenty-two healthy low-weight preterm newborns of both sexes were studied. None of them had neurological, cardiac and/or respiratory deficiencies. Assessments were made after the newborn had been left in an ordinary cot for 30 minutes and after 30 minutes of kangaroo mother care, on three consecutive days. For these evaluations, a heart monitor with a device for non-invasively measuring mean arterial pressure, a sensor for pulse oximetry, a thermometer and a chronometer were utilized. RESULTS: There were no significant changes in mean arterial pressure (p> 0.05 or heart rate (p> 0.05 after applying kangaroo mother care. However, there were significant increases in axillary temperature (p< 0.05 and peripheral oxygen

  12. Nonlinear cochlear mechanics.

    Science.gov (United States)

    Zweig, George

    2016-05-01

    An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis.

  13. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind P

    2001-01-01

    The Optical Society of America (OSA) and SPIE - The International Society for Optical Engineering have awarded Govind Agrawal with an honorable mention for the Joseph W. Goodman Book Writing Award for his work on Nonlinear Fiber Optics, 3rd edition.Nonlinear Fiber Optics, 3rd Edition, provides a comprehensive and up-to-date account of the nonlinear phenomena occurring inside optical fibers. It retains most of the material that appeared in the first edition, with the exception of Chapter 6, which is now devoted to the polarization effects relevant for light propagation in optical

  14. Will Nonlinear Backcalculation Help?

    DEFF Research Database (Denmark)

    Ullidtz, Per

    2000-01-01

    demonstrates, that treating the subgrade as a nonlinear elastic material, can result in more realistic moduli and a much better agreement between measured and calculated stresses and strains.The response of nonlinear elastic materials can be calculated using the Finite Element Method (FEM). A much simpler...... approach is to use the Method of Equivalent Thicknesses (MET), modified for a nonlinear subgrade. The paper includes an example where moduli backcalculated using FEM, linear elastic theory and MET are compared. Stresses and strains predicted by the three methods are also compared to measured values...

  15. Nonlinear graphene metamaterial

    CERN Document Server

    Nikolaenko, Andrey E; Atmatzakis, Evangelos; Luo, Zhiqiang; Shen, Ze Xiang; De Angelis, Francesco; Boden, Stuart A; Di Fabrizio, Enzo; Zheludev, Nikolay I

    2012-01-01

    We demonstrate that the broadband nonlinear optical response of graphene can be resonantly enhanced by more than an order of magnitude through hybridization with a plasmonic metamaterial,while retaining an ultrafast nonlinear response time of ~1 ps. Transmission modulation close to ~1% is seen at a pump uence of ~0.03 mJ/cm^2 at the wavelength of ~1600 nm. This approach allows to engineer and enhance graphene's nonlinearity within a broad wavelength range enabling applications in optical switching, mode-locking and pulse shaping.

  16. Multipolar nonlinear nanophotonics

    CERN Document Server

    Smirnova, Daria

    2016-01-01

    Nonlinear nanophotonics is a rapidly developing field with many useful applications for a design of nonlinear nanoantennas, light sources, nanolasers, sensors, and ultrafast miniature metadevices. A tight confinement of the local electromagnetic fields in resonant photonic nanostructures can boost nonlinear optical effects, thus offering versatile opportunities for subwavelength control of light. To achieve the desired functionalities, it is essential to gain flexible control over the near- and far-field properties of nanostructures. Thus, both modal and multipolar analyses are widely exploited for engineering nonlinear scattering from resonant nanoscale elements, in particular for enhancing the near-field interaction, tailoring the far-field multipolar interference, and optimization of the radiation directionality. Here, we review the recent advances in this recently emerged research field ranging from metallic structures exhibiting localized plasmonic resonances to hybrid metal-dielectric and all-dielectric...

  17. Solitons in nonlinear lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2010-01-01

    This article offers a comprehensive survey of results obtained for solitons and complex nonlinear wave patterns supported by purely nonlinear lattices (NLs), which represent a spatially periodic modulation of the local strength and sign of the nonlinearity, and their combinations with linear lattices. A majority of the results obtained, thus far, in this field and reviewed in this article are theoretical. Nevertheless, relevant experimental settings are surveyed too, with emphasis on perspectives for implementation of the theoretical predictions in the experiment. Physical systems discussed in the review belong to the realms of nonlinear optics (including artificial optical media, such as photonic crystals, and plasmonics) and Bose-Einstein condensation (BEC). The solitons are considered in one, two, and three dimensions (1D, 2D, and 3D). Basic properties of the solitons presented in the review are their existence, stability, and mobility. Although the field is still far from completion, general conclusions c...

  18. Nonlinear plasmonic antennas

    Directory of Open Access Journals (Sweden)

    Shakeeb Bin Hasan

    2014-12-01

    Full Text Available Contrary to traditional optical elements, plasmonic antennas made from nanostructured metals permit the localization of electromagnetic fields on length scales much smaller than the wavelength of light. This results in huge amplitudes for the electromagnetic field close to the antenna being conducive for the observation of nonlinear effects already at moderate pump powers. Thus, these antennas exhibit a promising potential to achieve optical frequency conversion and all-optical control of light at the nano-scale. This opens unprecedented opportunities for ultrafast nonlinear spectroscopy, sensing devices, on-chip optical frequency conversion, nonlinear optical metamaterials, and novel photon sources. Here, we review some of the recent advances in exploiting the potential of plasmonic antennas to realize robust nonlinear applications.

  19. Ultrafast nonlinear optics

    CERN Document Server

    Leburn, Christopher; Reid, Derryck

    2013-01-01

    The field of ultrafast nonlinear optics is broad and multidisciplinary, and encompasses areas concerned with both the generation and measurement of ultrashort pulses of light, as well as those concerned with the applications of such pulses. Ultrashort pulses are extreme events – both in terms of their durations, and also the high peak powers which their short durations can facilitate. These extreme properties make them powerful experiment tools. On one hand, their ultrashort durations facilitate the probing and manipulation of matter on incredibly short timescales. On the other, their ultrashort durations can facilitate high peak powers which can drive highly nonlinear light-matter interaction processes. Ultrafast Nonlinear Optics covers a complete range of topics, both applied and fundamental in nature, within the area of ultrafast nonlinear optics. Chapters 1 to 4 are concerned with the generation and measurement of ultrashort pulses. Chapters 5 to 7 are concerned with fundamental applications of ultrasho...

  20. Nonlinear Source Emulator

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem

    and remains the prime source of energy in non-terrestrial applications such as those in sky-explorers. However, a renewable energy source is expensive, bulky, and its performance is weather dependent, which make testing of downstream converters very difficult. As a result, a nonlinear source emulator (NSE......) is a good solution to solve the problems associated with the use of real nonlinear sources in testing phases. However, a recent technical survey conducted during this work shows that most existing NSEs have only been concerned with simulating nonlinear systems in terrestrial applications. Furthermore......, their dynamic performance were not fast enough in order to imitate how a real nonlinear energy source would react under extreme conditions and operation modes. Particularly, a system in the sky can experience a step change of sunlight irradiation. Moreover, operation modes may include load step between nominal...

  1. Introduction to nonlinear science

    CERN Document Server

    Nicolis, G

    1995-01-01

    One of the most unexpected results in science in recent years is that quite ordinary systems obeying simple laws can give rise to complex, nonlinear or chaotic, behavior. In this book, the author presents a unified treatment of the concepts and tools needed to analyze nonlinear phenomena and to outline some representative applications drawn from the physical, engineering, and biological sciences. Some of the interesting topics covered include: dynamical systems with a finite number of degrees of freedom, linear stability analysis of fixed points, nonlinear behavior of fixed points, bifurcation analysis, spatially distributed systems, broken symmetries, pattern formation, and chaotic dynamics. The author makes a special effort to provide a logical connection between ordinary dynamical systems and spatially extended systems, and to balance the emphasis on chaotic behavior and more classical nonlinear behavior. He also develops a statistical approach to complex systems and compares it to traditional deterministi...

  2. Nonlinear magnetoinductive transmission lines

    CERN Document Server

    Lazarides, Nikos; Tsironis, G P

    2011-01-01

    Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent cap...

  3. Optimization under Nonlinear Constraints

    OpenAIRE

    1982-01-01

    In this paper a timesaving method is proposed for maximizing likelihood functions when the parameter space is subject to nonlinear constraints, expressible as second order polynomials. The suggested approach is especially attractive when dealing with systems with many parameters.

  4. Nonlinearity in nanomechanical cantilevers

    DEFF Research Database (Denmark)

    Villanueva Torrijo, Luis Guillermo; Karabalin, R. B.; Matheny, M. H.

    2013-01-01

    Euler-Bernoulli beam theory is widely used to successfully predict the linear dynamics of micro-and nanocantilever beams. However, its capacity to characterize the nonlinear dynamics of these devices has not yet been rigorously assessed, despite its use in nanoelectromechanical systems development....... These findings underscore the delicate balance between inertial and geometric nonlinear effects in the fundamental mode, and strongly motivate further work to develop theories beyond the Euler-Bernoulli approximation. DOI: 10.1103/PhysRevB.87.024304....... In this article, we report the first highly controlled measurements of the nonlinear response of nanomechanical cantilevers using an ultralinear detection system. This is performed for an extensive range of devices to probe the validity of Euler-Bernoulli theory in the nonlinear regime. We find that its...

  5. Nonlinear Stokes Mueller Polarimetry

    CERN Document Server

    Samim, Masood; Barzda, Virginijus

    2015-01-01

    The Stokes Mueller polarimetry is generalized to include nonlinear optical processes such as second- and third-harmonic generation, sum- and difference-frequency generations. The overall algebraic form of the polarimetry is preserved, where the incoming and outgoing radiations are represented by column vectors and the intervening medium is represented by a matrix. Expressions for the generalized nonlinear Stokes vector and the Mueller matrix are provided in terms of coherency and correlation matrices, expanded by higher-dimensional analogues of Pauli matrices. In all cases, the outgoing radiation is represented by the conventional $4\\times 1$ Stokes vector, while dimensions of the incoming radiation Stokes vector and Mueller matrix depend on the order of the process being examined. In addition, relation between nonlinear susceptibilities and the measured Mueller matrices are explicitly provided. Finally, the approach of combining linear and nonlinear optical elements is discussed within the context of polarim...

  6. Adaptive and Nonlinear Control

    Science.gov (United States)

    1992-02-29

    in [22], we also applied the concept of zero dynamics to the problem of exact linearization of a nonlinear control system by dynamic feedback. Exact ...nonlinear systems, although it was well-known that the conditions for exact linearization are very stringent and consequently do not apply to a broad...29th IEEE Conference n Decision and Control, Invited Paper delivered by Dr. Gilliam. Exact Linearization of Zero Dynamics, 29th IEEE Conference on

  7. Nonlinear Optics and Turbulence

    Science.gov (United States)

    1992-10-01

    currently at Queen Mary College, London Patrick Dunne, (Ph.D., 1987, M.I.T., Hydrodynamic Stability, Nonlinear Waves), 1987-1988. Alecsander Dyachenko...U I I I U I I 3 9 3 V. BIOGRAPHIES A. FACULTY BRUCE BAYLY, 31, Ph.D. 1986, Princeton University. Postdoctoral visiting member 1986-88 at Courant...Caputo, A. C. Newell, and M. Shelley , "Nonlinear Wave Propagation Through a Random Medium and Soliton Tunneling", Integrable Systems and

  8. Robust Nonlinear Neural Codes

    Science.gov (United States)

    Yang, Qianli; Pitkow, Xaq

    2015-03-01

    Most interesting natural sensory stimuli are encoded in the brain in a form that can only be decoded nonlinearly. But despite being a core function of the brain, nonlinear population codes are rarely studied and poorly understood. Interestingly, the few existing models of nonlinear codes are inconsistent with known architectural features of the brain. In particular, these codes have information content that scales with the size of the cortical population, even if that violates the data processing inequality by exceeding the amount of information entering the sensory system. Here we provide a valid theory of nonlinear population codes by generalizing recent work on information-limiting correlations in linear population codes. Although these generalized, nonlinear information-limiting correlations bound the performance of any decoder, they also make decoding more robust to suboptimal computation, allowing many suboptimal decoders to achieve nearly the same efficiency as an optimal decoder. Although these correlations are extremely difficult to measure directly, particularly for nonlinear codes, we provide a simple, practical test by which one can use choice-related activity in small populations of neurons to determine whether decoding is suboptimal or optimal and limited by correlated noise. We conclude by describing an example computation in the vestibular system where this theory applies. QY and XP was supported by a grant from the McNair foundation.

  9. Nonlinear Multiantenna Detection Methods

    Directory of Open Access Journals (Sweden)

    Chen Sheng

    2004-01-01

    Full Text Available A nonlinear detection technique designed for multiple-antenna assisted receivers employed in space-division multiple-access systems is investigated. We derive the optimal solution of the nonlinear spatial-processing assisted receiver for binary phase shift keying signalling, which we refer to as the Bayesian detector. It is shown that this optimal Bayesian receiver significantly outperforms the standard linear beamforming assisted receiver in terms of a reduced bit error rate, at the expense of an increased complexity, while the achievable system capacity is substantially enhanced with the advent of employing nonlinear detection. Specifically, when the spatial separation expressed in terms of the angle of arrival between the desired and interfering signals is below a certain threshold, a linear beamformer would fail to separate them, while a nonlinear detection assisted receiver is still capable of performing adequately. The adaptive implementation of the optimal Bayesian detector can be realized using a radial basis function network. Two techniques are presented for constructing block-data-based adaptive nonlinear multiple-antenna assisted receivers. One of them is based on the relevance vector machine invoked for classification, while the other on the orthogonal forward selection procedure combined with the Fisher ratio class-separability measure. A recursive sample-by-sample adaptation procedure is also proposed for training nonlinear detectors based on an amalgam of enhanced -means clustering techniques and the recursive least squares algorithm.

  10. Nonlinear systems in medicine.

    Science.gov (United States)

    Higgins, John P

    2002-01-01

    Many achievements in medicine have come from applying linear theory to problems. Most current methods of data analysis use linear models, which are based on proportionality between two variables and/or relationships described by linear differential equations. However, nonlinear behavior commonly occurs within human systems due to their complex dynamic nature; this cannot be described adequately by linear models. Nonlinear thinking has grown among physiologists and physicians over the past century, and non-linear system theories are beginning to be applied to assist in interpreting, explaining, and predicting biological phenomena. Chaos theory describes elements manifesting behavior that is extremely sensitive to initial conditions, does not repeat itself and yet is deterministic. Complexity theory goes one step beyond chaos and is attempting to explain complex behavior that emerges within dynamic nonlinear systems. Nonlinear modeling still has not been able to explain all of the complexity present in human systems, and further models still need to be refined and developed. However, nonlinear modeling is helping to explain some system behaviors that linear systems cannot and thus will augment our understanding of the nature of complex dynamic systems within the human body in health and in disease states.

  11. Handbook of nonlinear optical crystals

    CERN Document Server

    Dmitriev, Valentin G; Nikogosyan, David N

    1991-01-01

    This Handbook of Nonlinear Optical Crystals provides a complete description of the properties and applications of nonlinear crystals In addition, it presents the most important equations for calculating the main parameters of nonlinear frequency converters This comprehensive reference work will be of great value to all scientists and engineers working in nonlinear optics, quantum electronics and laser physics

  12. Research on dynamics coupling for underactuated bionic kangaroo-hopping robot%欠驱动仿袋鼠跳跃机器人动力学耦合研究

    Institute of Scientific and Technical Information of China (English)

    陈朋威; 葛文杰; 李岩

    2012-01-01

    根据袋鼠的生物结构及运动特点,建立了具有欠驱动关节的仿袋鼠跳跃机器人模型.以此模型为基础,分析系统的主动关节与被动关节之间的加速度耦合效应.采用拉格朗日方方法建立了机构的动力学方程.结合实例,运用Matlab软件对机器人进行仿真分析,给出了机器人全局单关节耦合变化规律.结果表明:仿袋鼠跳跃机器人的踝关节与欠驱动关节间存在足够大的耦合并且通过动力学耦合来控制欠驱动关节的位置是可能的.动力学耦合指标对欠驱动机器人的结构设计和驱动装置位置有重要作用.%According to the biological structure and kinematic characteristics of kangaroo, we establish a model for uniped hopping mechanism of bionic kangaroo with underactuated joint.Based on this model,the dynamic coupling effects of the acceleration coupling between active joints and passive ones are an-alyzed,and dynamics equations are established with adopting lagrange method.Wuh practical example and using Matlab simulation analysis for the robot is made so that the changing rule of the global individual joint coupling are obtained.The result indicates that a large coupling between the ankle joint and underactuated joint of the hopping kangaroo robot is available, thus it is possible to control the position of the under-actuated joint via the dynamics coupling, which index plays an important role in structure design and actuator placement of underactuated robots system.

  13. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  14. Nonlinear pulsation masses

    Energy Technology Data Exchange (ETDEWEB)

    Davis, C.G.

    1990-01-01

    The advent of nonlinear pulsation theory really coincides with the development of the large computers after the second world war. Christy and Stobbie were the first to make use of finite difference techniques on computers to model the bumps'' observed in the classical Cepheid light and velocity curves, the so-called Hertzsprung'' sequence. Following this work a more sophisticated analysis of the light and velocity curves from the models was made by Simon and Davis using Fourier techniques. Recently a simpler amplitude equation formalism has been developed that helps explain this resonance mechanism. The determination of Population I Cepheid masses by nonlinear methods will be discussed. For the lower mass objects, such as RR Lyrae and BL Her. stars, we find general agreement using evolutionary masses and nonlinear pulsation theory. An apparent difficulty of nonlinear pulsation theory occurs in the understanding of double'' mode pulsation, which will also be discussed. Recent studies in nonlinear pulsation theory have dealt with the question of mode selection, period doubling and the trends towards chaotic behavior such as is observed in the transition from W Virginis to RV Tauri-like stars. 10 refs., 1 fig., 2 tabs.

  15. Research progress on kangaroo mother care in nursing of preterm infants%袋鼠式护理在早产儿护理中的研究进展

    Institute of Scientific and Technical Information of China (English)

    田莉; 丁晓华; 武玉蓉

    2011-01-01

    With the development of perinatology and neonatology,the survival rate of preterm infants was improved a lot,the preterm infants become one of the important study in nowdays.there have been many studies about nursing of preterm infants,This article summarizes research progress on kangaroo mother care in nursing of preterm infants.%随着围产医学和新生儿医学的迅速发展,早产儿的存活率得到极大提高,早产儿成为当今研究的重要内容之一.有关早产儿护理干预的研究也很多,现就袋鼠式护理在早产儿护理中的研究进展综述如下.

  16. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  17. Nonlinear Dynamic Force Spectroscopy

    CERN Document Server

    Björnham, Oscar

    2016-01-01

    Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...

  18. Nonlinear optomechanical paddle nanocavities

    CERN Document Server

    Kaviani, Hamidreza; Wu, Marcelo; Ghobadi, Roohollah; Barclay, Paul E

    2014-01-01

    A photonic crystal optomechanical system combining strong nonlinear optomechanical coupling, low effective mass and large optical mode spacing is introduced. This nanoscale "paddle nanocavity" device supports mechanical resonances with effective mass of 300--600 fg which couple nonlinearly to co-localized optical modes with a quadratic optomechanical coupling coefficient $g^{(2)} > 2\\pi\\times400$ MHz/nm$^2$, and a two phonon to single photon optomechanical coupling rate $\\Delta \\omega_0 > 2\\pi\\times 16$ Hz. This coupling relies on strong phonon-photon interactions in a structure whose optical mode spectrum is highly non--degenerate. Simulations indicate that nonlinear optomechanical readout of thermally driven motion in these devices should be observable for T $> 50 $ mK, and that measurement of phonon shot noise is achievable.

  19. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  20. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    , leading to reduced mode confinement and dispersion flexibility. In this thesis, we treat the nonlinear photonic crystal fiber – a special sub-class of photonic crystal fibers, the core of which has a diameter comparable to the wavelength of the light guided in the fiber. The small core results in a large...... nonlinear coefficient and in various applications, it is therefore possible to reduce the required fiber lengths quite dramatically, leading to increased stability and efficiency. Furthermore, it is possible to design these fibers with zero-dispersion at previously unreachable wavelengths, paving the way...... for completely new applications, especially in and near the visible wavelength region. One such application is supercontinuum generation. Supercontinuum generation is extreme broadening of pulses in a nonlinear medium (in this case a small-core fiber), and depending on the dispersion of the fiber, it is possible...

  1. Linearizing nonlinear optics

    CERN Document Server

    Schmidt, Bruno E; Ernotte, Guilmot; Clerici, Matteo; Morandotti, Roberto; Ibrahim, Heide; Legare, Francois

    2016-01-01

    In the framework of linear optics, light fields do not interact with each other in a medium. Yet, when their field amplitude becomes comparable to the electron binding energies of matter, the nonlinear motion of these electrons emits new dipole radiation whose amplitude, frequency and phase differ from the incoming fields. Such high fields are typically achieved with ultra-short, femtosecond (1fs = 10-15 sec.) laser pulses containing very broad frequency spectra. Here, the matter not only couples incoming and outgoing fields but also causes different spectral components to interact and mix through a convolution process. In this contribution, we describe how frequency domain nonlinear optics overcomes the shortcomings arising from this convolution in conventional time domain nonlinear optics1. We generate light fields with previously inaccessible properties because the uncontrolled coupling of amplitudes and phases is turned off. For example, arbitrary phase functions are transferred linearly to the second har...

  2. Nonlinear optomechanics with graphene

    Science.gov (United States)

    Shaffer, Airlia; Patil, Yogesh Sharad; Cheung, Hil F. H.; Wang, Ke; Vengalattore, Mukund

    2016-05-01

    To date, studies of cavity optomechanics have been limited to exploiting the linear interactions between the light and mechanics. However, investigations of quantum signal transduction, quantum enhanced metrology and manybody physics with optomechanics each require strong, nonlinear interactions. Graphene nanomembranes are an exciting prospect for realizing such studies due to their inherently nonlinear nature and low mass. We fabricate large graphene nanomembranes and study their mechanical and optical properties. By using dark ground imaging techniques, we correlate their eigenmode shapes with the measured dissipation. We study their hysteretic response present even at low driving amplitudes, and their nonlinear dissipation. Finally, we discuss ongoing efforts to use these resonators for studies of quantum optomechanics and force sensing. This work is supported by the DARPA QuASAR program through a Grant from the ARO.

  3. Nonlinear Analysis of Buckling

    Directory of Open Access Journals (Sweden)

    Psotný Martin

    2014-06-01

    Full Text Available The stability analysis of slender web loaded in compression was presented. To solve this problem, a specialized computer program based on FEM was created. The nonlinear finite element method equations were derived from the variational principle of minimum of potential energy. To obtain the nonlinear equilibrium paths, the Newton-Raphson iteration algorithm was used. Corresponding levels of the total potential energy were defined. The peculiarities of the effects of the initial imperfections were investigated. Special attention was focused on the influence of imperfections on the post-critical buckling mode. The stable and unstable paths of the nonlinear solution were separated. Obtained results were compared with those gained using ANSYS system.

  4. Nonlinear Metamaterials for Holography

    CERN Document Server

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multi-layer metamaterial holograms where by the nonlinear process of Third Harmonic Generation, a background free image is formed at a new frequency which is the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analyzed and prospects for future device applications are discussed.

  5. Multidimensional nonlinear descriptive analysis

    CERN Document Server

    Nishisato, Shizuhiko

    2006-01-01

    Quantification of categorical, or non-numerical, data is a problem that scientists face across a wide range of disciplines. Exploring data analysis in various areas of research, such as the social sciences and biology, Multidimensional Nonlinear Descriptive Analysis presents methods for analyzing categorical data that are not necessarily sampled randomly from a normal population and often involve nonlinear relations. This reference not only provides an overview of multidimensional nonlinear descriptive analysis (MUNDA) of discrete data, it also offers new results in a variety of fields. The first part of the book covers conceptual and technical preliminaries needed to understand the data analysis in subsequent chapters. The next two parts contain applications of MUNDA to diverse data types, with each chapter devoted to one type of categorical data, a brief historical comment, and basic skills peculiar to the data types. The final part examines several problems and then concludes with suggestions for futu...

  6. Nonlinear airship aeroelasticity

    Science.gov (United States)

    Bessert, N.; Frederich, O.

    2005-12-01

    The aeroelastic derivatives for today's aircraft are calculated in the concept phase using a standard procedure. This scheme has to be extended for large airships, due to various nonlinearities in structural and aerodynamic behaviour. In general, the structural model of an airship is physically as well as geometrically nonlinear. The main sources of nonlinearity are large deformations and the nonlinear material behaviour of membranes. The aerodynamic solution is also included in the nonlinear problem, because the deformed airship influences the surrounding flow. Due to these nonlinearities, the aeroelastic problem for airships can only be solved by an iterative procedure. As one possibility, the coupled aerodynamic and structural dynamic problem was handled using linked standard solvers. On the structural side, the Finite-Element program package ABAQUS was extended with an interface to the aerodynamic solver VSAERO. VSAERO is based on the aerodynamic panel method using potential flow theory. The equilibrium of the internal structural and the external aerodynamic forces leads to the structural response and a trimmed flight state for the specified flight conditions (e.g. speed, altitude). The application of small perturbations around a trimmed state produces reaction forces and moments. These constraint forces are then transferred into translational and rotational acceleration fields by performing an inertia relief analysis of the disturbed structural model. The change between the trimmed flight state and the disturbed one yields the respective aeroelastic derivatives. By including the calculated derivatives in the linearised equation of motion system, it is possible to judge the stability and controllability of the investigated airship.

  7. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  8. Limits to Nonlinear Inversion

    DEFF Research Database (Denmark)

    Mosegaard, Klaus

    2012-01-01

    For non-linear inverse problems, the mathematical structure of the mapping from model parameters to data is usually unknown or partly unknown. Absence of information about the mathematical structure of this function prevents us from presenting an analytical solution, so our solution depends on our......-heuristics are inefficient for large-scale, non-linear inverse problems, and that the 'no-free-lunch' theorem holds. We discuss typical objections to the relevance of this theorem. A consequence of the no-free-lunch theorem is that algorithms adapted to the mathematical structure of the problem perform more efficiently than...

  9. Fundamentals of nonlinear optics

    CERN Document Server

    Powers, Peter E

    2011-01-01

    Peter Powers's rigorous but simple description of a difficult field keeps the reader's attention throughout. … All chapters contain a list of references and large numbers of practice examples to be worked through. … By carefully working through the proposed problems, students will develop a sound understanding of the fundamental principles and applications. … the book serves perfectly for an introductory-level course for second- and third-order nonlinear optical phenomena. The author's writing style is refreshing and original. I expect that Fundamentals of Nonlinear Optics will fast become pop

  10. Tunable nonlinear graphene metasurfaces

    CERN Document Server

    Smirnova, Daria A; Kivshar, Yuri S; Khanikaev, Alexander B

    2015-01-01

    We introduce the concept of nonlinear graphene metasurfaces employing the controllable interaction between a graphene layer and a planar metamaterial. Such hybrid metasurfaces support two types of subradiant resonant modes, asymmetric modes of structured metamaterial elements ("metamolecules") and graphene plasmons exhibiting strong mutual coupling and avoided dispersion crossing. High tunability of graphene plasmons facilitates strong interaction between the subradiant modes, modifying the spectral position and lifetime of the associated Fano resonances. We demonstrate that strong resonant interaction, combined with the subwavelength localization of plasmons, leads to the enhanced nonlinear response and high efficiency of the second-harmonic generation.

  11. Nonlinear effects in optical fibers

    CERN Document Server

    Ferreira, Mario F

    2011-01-01

    Cutting-edge coverage of nonlinear phenomena occurring inside optical fibers Nonlinear fiber optics is a specialized part of fiber optics dealing with optical nonlinearities and their applications. As fiber-optic communication systems have become more advanced and complex, the nonlinear effects in optical fibers have increased in importance, as they adversely affect system performance. Paradoxically, the same nonlinear phenomena also offer the promise of addressing the bandwidth bottleneck for signal processing for future ultra-high speed optical networks. Nonlinear Effects in Optical Fiber

  12. Nonlinear elliptic systems with exponential nonlinearities

    Directory of Open Access Journals (Sweden)

    Said El Manouni

    2002-12-01

    Full Text Available In this paper we investigate the existence of solutions for {gather*} -mathop{m div}( a(| abla u | ^N| abla u |^{N-2}u = f(x,u,v quad mbox{in } Omega -mathop{m div}(a(| abla v| ^N| abla v |^{N-2}v = g(x,u,v quad mbox{in } Omega u(x = v(x = 0 quad mbox{on }partial Omega. end{gather*} Where $Omega$ is a bounded domain in ${mathbb{R}}^N$, $Ngeq 2$, $f$ and $g$ are nonlinearities having an exponential growth on $Omega$ and $a$ is a continuous function satisfying some conditions which ensure the existence of solutions.

  13. Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

    2001-01-01

    We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...

  14. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-10-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  15. Nonlinear Regression with R

    CERN Document Server

    Ritz, Christian; Parmigiani, Giovanni

    2009-01-01

    R is a rapidly evolving lingua franca of graphical display and statistical analysis of experiments from the applied sciences. This book provides a coherent treatment of nonlinear regression with R by means of examples from a diversity of applied sciences such as biology, chemistry, engineering, medicine and toxicology.

  16. Methods of nonlinear kinetics

    OpenAIRE

    Gorban, A. N.; Karlin, I.V.

    2003-01-01

    Nonlinear kinetic equations are reviewed for a wide audience of specialists and postgraduate students in physics, mathematical physics, material science, chemical engineering and interdisciplinary research. Contents: The Boltzmann equation, Phenomenology and Quasi-chemical representation of the Boltzmann equation, Kinetic models, Discrete velocity models, Direct simulation, Lattice Gas and Lattice Boltzmann models, Minimal Boltzmann models for flows at low Knudsen number, Other kinetic equati...

  17. Intramolecular and nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Davis, M.J. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

  18. Nonlinear Hamiltonian systems

    DEFF Research Database (Denmark)

    Jørgensen, Michael Finn

    1995-01-01

    It is generally very difficult to solve nonlinear systems, and such systems often possess chaotic solutions. In the rare event that a system is completely solvable, it is said to integrable. Such systems never have chaotic solutions. Using the Inverse Scattering Transform Method (ISTM) two...

  19. Nonlinear phased array imaging

    Science.gov (United States)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  20. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-11-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  1. Trirefringence in nonlinear metamaterials

    CERN Document Server

    De Lorenci, Vitorio A

    2012-01-01

    We study the propagation of electromagnetic waves in the limit of geometrical optics for a class of nearly transparent nonlinear uniaxial metamaterials for which their permittivity tensors present a negative principal component. Their permeability are assumed positive and dependent on the electric field. We show that light waves experience triple refraction -- trirefringence. Additionally to the ordinary wave, two extraordinary waves propagate in such media.

  2. Nonlinear silicon photonics

    Science.gov (United States)

    Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

    2017-09-01

    Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

  3. Nonlinear fibre optics overview

    DEFF Research Database (Denmark)

    Travers, J. C.; Frosz, Michael Henoch; Dudley, J. M.

    2010-01-01

    , provides a background to the associated nonlinear optical processes, treats the generation mechanisms from continuous wave to femtosecond pulse pump regimes and highlights the diverse applications. A full discussion of numerical methods and comprehensive computer code are also provided, enabling readers...

  4. Nonlinear silicon photonics

    Science.gov (United States)

    Tsia, Kevin K.; Jalali, Bahram

    2010-05-01

    An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

  5. Is this scaling nonlinear?

    CERN Document Server

    Leitao, J C; Gerlach, M; Altmann, E G

    2016-01-01

    One of the most celebrated findings in complex systems in the last decade is that different indexes y (e.g., patents) scale nonlinearly with the population~x of the cities in which they appear, i.e., $y\\sim x^\\beta, \\beta \

  6. Nonlinear Gravitational Lagrangians revisited

    CERN Document Server

    Magnano, Guido

    2016-01-01

    The Legendre transformation method, applied in 1987 to deal with purely metric gravitational Lagrangians with nonlinear dependence on the Ricci tensor, is extended to metric-affine models and is shown to provide a concise and insightful comparison of the dynamical content of the two variational frameworks.

  7. Nonlinearities in Microwave Superconductivity

    OpenAIRE

    Ledenyov, Dimitri O.; Ledenyov, Viktor O.

    2012-01-01

    The research is focused on the modeling of nonlinear properties of High Temperature Superconducting (HTS) thin films, using Bardeen, Cooper, Schrieffer and Lumped Element Circuit theories, with purpose to enhance microwave power handling capabilities of microwave filters and optimize design of microwave circuits in micro- and nano- electronics.

  8. Nonlinear tsunami generation mechanism

    Directory of Open Access Journals (Sweden)

    M. A. Nosov

    2001-01-01

    Full Text Available The nonlinear mechanism of long gravitational surface water wave generation by high-frequency bottom oscillations in a water layer of constant depth is investigated analytically. The connection between the surface wave amplitude and the parameters of bottom oscillations and source length is investigated.

  9. Topics in Nonlinear Dynamics

    DEFF Research Database (Denmark)

    Mosekilde, Erik

    Through a significant number of detailed and realistic examples this book illustrates how the insights gained over the past couple of decades in the fields of nonlinear dynamics and chaos theory can be applied in practice. Aomng the topics considered are microbiological reaction systems, ecological...

  10. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...

  11. Nonlinear Optical Terahertz Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Our approach is based on high-Q optical WGM resonators made with a nonlinear crystal. Such resonators have been demonstrated to dramatically enhance nonlinear...

  12. Phase retrieval using nonlinear diversity.

    Science.gov (United States)

    Lu, Chien-Hung; Barsi, Christopher; Williams, Matthew O; Kutz, J Nathan; Fleischer, Jason W

    2013-04-01

    We extend the Gerchberg-Saxton algorithm to phase retrieval in a nonlinear system. Using a tunable photorefractive crystal, we experimentally demonstrate the noninterferometric technique by reconstructing an unknown phase object from optical intensity measurements taken at different nonlinear strengths.

  13. Strong nonlinear oscillators analytical solutions

    CERN Document Server

    Cveticanin, Livija

    2017-01-01

    This book outlines an analytical solution procedure of the pure nonlinear oscillator system, offering a solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter. Includes exercises.

  14. Cubication of Conservative Nonlinear Oscillators

    Science.gov (United States)

    Belendez, Augusto; Alvarez, Mariela L.; Fernandez, Elena; Pascual, Immaculada

    2009-01-01

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear…

  15. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...

  16. Fault Detection for Nonlinear Systems

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.H.

    1998-01-01

    The paper describes a general method for designing fault detection and isolation (FDI) systems for nonlinear processes. For a rich class of nonlinear systems, a nonlinear FDI system can be designed using convex optimization procedures. The proposed method is a natural extension of methods based...

  17. Nonlinear electrostatic drift Kelvin-Helmholtz instability

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1993-01-01

    Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves, and the nonlinear behavior is governed by the nonlinear Burger's equation.

  18. Optothermal nonlinearity of silica aerogel

    CERN Document Server

    Braidotti, Maria Chiara; Fleming, Adam; Samuels, Michiel C; Di Falco, Andrea; Conti, Claudio

    2016-01-01

    We report on the characterization of silica aerogel thermal optical nonlinearity, obtained by z-scan technique. The results show that typical silica aerogels have nonlinear optical coefficient similar to that of glass $(\\simeq 10^{-12} $m$^2/$W), with negligible optical nonlinear absorption. The non\\-li\\-near coefficient can be increased to values in the range of $10^{-10} $m$^2/$W by embedding an absorbing dye in the aerogel. This value is one order of magnitude higher than that observed in the pure dye and in typical highly nonlinear materials like liquid crystals.

  19. Essentials of nonlinear optics

    CERN Document Server

    Murti, Y V G S

    2014-01-01

    Current literature on Nonlinear Optics varies widely in terms of content, style, and coverage of specific topics, relative emphasis of areas and the depth of treatment. While most of these books are excellent resources for the researchers, there is a strong need for books appropriate for presenting the subject at the undergraduate or postgraduate levels in Universities. The need for such a book to serve as a textbook at the level of the bachelors and masters courses was felt by the authors while teaching courses on nonlinear optics to students of both science and engineering during the past two decades. This book has emerged from an attempt to address the requirement of presenting the subject at college level. A one-semester course covering the essentials can effectively be designed based on this.

  20. Nonlinear metamaterials for holography

    Science.gov (United States)

    Almeida, Euclides; Bitton, Ora; Prior, Yehiam

    2016-08-01

    A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three-dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years, it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multilayer metamaterial holograms. A background free image is formed at a new frequency--the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analysed and prospects for future device applications are discussed.

  1. Nonlinear metamaterials for holography

    Science.gov (United States)

    Almeida, Euclides; Bitton, Ora

    2016-01-01

    A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three-dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years, it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multilayer metamaterial holograms. A background free image is formed at a new frequency—the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analysed and prospects for future device applications are discussed. PMID:27545581

  2. Nonlinear data assimilation

    CERN Document Server

    Van Leeuwen, Peter Jan; Reich, Sebastian

    2015-01-01

    This book contains two review articles on nonlinear data assimilation that deal with closely related topics but were written and can be read independently. Both contributions focus on so-called particle filters. The first contribution by Jan van Leeuwen focuses on the potential of proposal densities. It discusses the issues with present-day particle filters and explorers new ideas for proposal densities to solve them, converging to particle filters that work well in systems of any dimension, closing the contribution with a high-dimensional example. The second contribution by Cheng and Reich discusses a unified framework for ensemble-transform particle filters. This allows one to bridge successful ensemble Kalman filters with fully nonlinear particle filters, and allows a proper introduction of localization in particle filters, which has been lacking up to now.

  3. Nonlinearity without Superluminality

    CERN Document Server

    Kent, A

    2002-01-01

    Quantum theory is compatible with special relativity. In particular, though measurements on entangled systems are correlated in a way that cannot be reproduced by local hidden variables, they cannot be used for superluminal signalling. As Gisin and Polchinski first pointed out, this is not true for general nonlinear modifications of the Schroedinger equation. Excluding superluminal signalling has thus been taken to rule out most nonlinear versions of quantum theory. The no superluminal signalling constraint has also been used for alternative derivations of the optimal fidelities attainable for imperfect quantum cloning and other operations. These results apply to theories satisfying the rule that their predictions for widely separated and slowly moving entangled systems can be approximated by non-relativistic equations of motion with respect to a preferred time coordinate. This paper describes a natural way in which this rule might fail to hold. In particular, it is shown that quantum readout devices which di...

  4. Monte Carlo and nonlinearities

    CERN Document Server

    Dauchet, Jérémi; Blanco, Stéphane; Caliot, Cyril; Charon, Julien; Coustet, Christophe; Hafi, Mouna El; Eymet, Vincent; Farges, Olivier; Forest, Vincent; Fournier, Richard; Galtier, Mathieu; Gautrais, Jacques; Khuong, Anaïs; Pelissier, Lionel; Piaud, Benjamin; Roger, Maxime; Terrée, Guillaume; Weitz, Sebastian

    2016-01-01

    The Monte Carlo method is widely used to numerically predict systems behaviour. However, its powerful incremental design assumes a strong premise which has severely limited application so far: the estimation process must combine linearly over dimensions. Here we show that this premise can be alleviated by projecting nonlinearities on a polynomial basis and increasing the configuration-space dimension. Considering phytoplankton growth in light-limited environments, radiative transfer in planetary atmospheres, electromagnetic scattering by particles and concentrated-solar-power-plant productions, we prove the real world usability of this advance on four test-cases that were so far regarded as impracticable by Monte Carlo approaches. We also illustrate an outstanding feature of our method when applied to sharp problems with interacting particles: handling rare events is now straightforward. Overall, our extension preserves the features that made the method popular: addressing nonlinearities does not compromise o...

  5. Nonlinear Photonics 2014: introduction.

    Science.gov (United States)

    Akhmediev, N; Kartashov, Yaroslav

    2015-01-12

    International Conference "Nonlinear Photonics-2014" took place in Barcelona, Spain on July 27-31, 2014. It was a part of the "Advanced Photonics Congress" which is becoming a traditional notable event in the world of photonics. The current focus issue of Optics Express contains contributions from the participants of the Conference and the Congress. The articles in this focus issue by no means represent the total number of the congress contributions (around 400). However, it demonstrates wide range of topics covered at the event. The next conference of this series is to be held in 2016 in Australia, which is the home of many researchers working in the field of photonics in general and nonlinear photonics in particular.

  6. The Meta Analysis of Alleviatory Effect of Kangaroo Care on Neonatal Painful Caused by Invasive Operation%袋鼠式护理缓解侵入性操作所致新生儿疼痛的Meta分析

    Institute of Scientific and Technical Information of China (English)

    朴海善; 王松; 李胜玲

    2012-01-01

    目的 通过对袋鼠式护理缓解侵入性操作所致新生儿疼痛的随机对照试验和(或)临床对照试验文献进行Meta分析,客观评价袋鼠式护理的效果,为临床新生儿疼痛的管理提供理论依据.方法 联机检索在线PUBMED、EBSCO、OVID、EMBASE、Cochrane library、中国知网、中国生物医学文献数据库,并以手工检索和引文检索为辅助,全面获取有关袋鼠式护理缓解侵入性操作所致新生儿疼痛的中英文文献.对符合纳入标准的文献,由两名研究者独立进行方法学质量评价和资料提取.采用RevMan5.0.25统计软件进行meta分析.结果 经筛选共纳入7篇临床对照试验文献.Meta分析结果显示:袋鼠式护理和襁褓包裹比较,更能稳定新生儿侵入性操作期间和操作后恢复期的心率及血氧饱和度(P<0.01),可缩短新生儿侵入性操作时和操作后恢复期啼哭和疼痛面容的持续时间(P<0.01),可减少新生儿侵入性操作时的NFCS评分(P<0.01).结论 袋鼠式护理可以有效缓解新生儿对疼痛的生理反应和行为反应,减轻新生儿疼痛.由于相关研究较少,今后尚需纳入更多设计严格的大样本随机对照试验以进一步评价袋鼠式护理缓解新生儿疼痛的效果.%Objective To evaluate the alleviatory effect of kangaroo care on neonatal pain caused by invasive operation using Meta analysis. Methods With the computer retrieval of PUBMED/MEDLINE , EBSCO, OVID, EMBASE, Cochrane library, CNKI, CMBI and auxiliary manual retrieval, citation retrieval as well, the author tried to gain the documents comprehensively in both Chinese and English on the kangaroo care easing neonatal pain caused by invasive operation. To the included documents fit for standard, two researchers were planned to screen them and then to make a methodological quality evaluation and material extraction independently. The RevMan5.0.25 statistical software for Meta analysis was used. Results After

  7. Nonlinear fractional relaxation

    Indian Academy of Sciences (India)

    A Tofighi

    2012-04-01

    We define a nonlinear model for fractional relaxation phenomena. We use -expansion method to analyse this model. By studying the fundamental solutions of this model we find that when → 0 the model exhibits a fast decay rate and when → ∞ the model exhibits a power-law decay. By analysing the frequency response we find a logarithmic enhancement for the relative ratio of susceptibility.

  8. -Deformed nonlinear maps

    Indian Academy of Sciences (India)

    Ramaswamy Jaganathan; Sudeshna Sinha

    2005-03-01

    Motivated by studies on -deformed physical systems related to quantum group structures, and by the elements of Tsallis statistical mechanics, the concept of -deformed nonlinear maps is introduced. As a specific example, a -deformation procedure is applied to the logistic map. Compared to the canonical logistic map, the resulting family of -logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors – a phenomenon rare in one-dimensional maps.

  9. Controllability of nonlinear systems.

    Science.gov (United States)

    Sussmann, H. J.; Jurdjevic, V.

    1972-01-01

    Discussion of the controllability of nonlinear systems described by the equation dx/dt - F(x,u). Concepts formulated by Chow (1939) and Lobry (1970) are applied to establish criteria for F and its derivatives to obtain qualitative information on sets which can be obtained from x which denotes a variable of state in an arbitrary, real, analytical manifold. It is shown that controllability implies strong accessibility for a large class of manifolds including Euclidean spaces.-

  10. Stochastic Nonlinear Aeroelasticity

    Science.gov (United States)

    2009-01-01

    STOCHASTIC NONLINEAR AEROELASTICITY 5a. CONTRACT NUMBER In- house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 0601102 6. AUTHOR(S) Philip S...ABSTRACT This report documents the culmination of in- house work in the area of uncertainty quantification and probabilistic techniques for... coff U∞ cs ea lw cw Figure 6: Wing and store geometry (left), wing box structural model (middle), flutter distribution (right

  11. Nonlinear Control Systems

    Science.gov (United States)

    2007-03-01

    IEEE Transactions on Automatic Control , AC- 48, pp. 1712-1723, (2003). [14] C.I. Byrnes, A. Isidori...Nonlinear internal models for output regulation,” IEEE Transactions on Automatic Control , AC-49, pp. 2244-2247, (2004). [15] C.I. Byrnes, F. Celani, A...approach,” IEEE Transactions on Automatic Control , 48 (Dec. 2003), 2172–2190. 2. C. I. Byrnes, “Differential Forms and Dynamical Systems,” to appear

  12. Filamentation with nonlinear Bessel vortices.

    Science.gov (United States)

    Jukna, V; Milián, C; Xie, C; Itina, T; Dudley, J; Courvoisier, F; Couairon, A

    2014-10-20

    We present a new type of ring-shaped filaments featured by stationary nonlinear high-order Bessel solutions to the laser beam propagation equation. Two different regimes are identified by direct numerical simulations of the nonlinear propagation of axicon focused Gaussian beams carrying helicity in a Kerr medium with multiphoton absorption: the stable nonlinear propagation regime corresponds to a slow beam reshaping into one of the stationary nonlinear high-order Bessel solutions, called nonlinear Bessel vortices. The region of existence of nonlinear Bessel vortices is found semi-analytically. The influence of the Kerr nonlinearity and nonlinear losses on the beam shape is presented. Direct numerical simulations highlight the role of attractors played by nonlinear Bessel vortices in the stable propagation regime. Large input powers or small cone angles lead to the unstable propagation regime where nonlinear Bessel vortices break up into an helical multiple filament pattern or a more irregular structure. Nonlinear Bessel vortices are shown to be sufficiently intense to generate a ring-shaped filamentary ionized channel in the medium which is foreseen as opening the way to novel applications in laser material processing of transparent dielectrics.

  13. Strongly nonlinear oscillators analytical solutions

    CERN Document Server

    Cveticanin, Livija

    2014-01-01

    This book provides the presentation of the motion of pure nonlinear oscillatory systems and various solution procedures which give the approximate solutions of the strong nonlinear oscillator equations. The book presents the original author’s method for the analytical solution procedure of the pure nonlinear oscillator system. After an introduction, the physical explanation of the pure nonlinearity and of the pure nonlinear oscillator is given. The analytical solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter is considered. Special attention is given to the one and two mass oscillatory systems with two-degrees-of-freedom. The criteria for the deterministic chaos in ideal and non-ideal pure nonlinear oscillators are derived analytically. The method for suppressing chaos is developed. Important problems are discussed in didactic exercises. The book is self-consistent and suitable as a textbook for students and also for profess...

  14. Quantum well nonlinear microcavities

    Science.gov (United States)

    Oudar, J. L.; Kuszelewicz, R.; Sfez, B.; Pellat, D.; Azoulay, R.

    We report on recent progress in reducing the power threshold of all-optical bistable quantum well vertical microcavities. Significant improvements are achieved through an increase of the cavity finesse, together with a reduction of the device active layer thickness. A critical intensity of 5 μW/μm 2 has been observed on a microcavity of finesse 250, with a nonlinear medium of only 18 GaAs quantum wells of 10 nm thickness. Further improvements of the Bragg mirror quality resulted in a finesse of 700 and a power-lifetime product of 15 fJ/μm 2. Microresonator pixellation allows to obtain 2-dimensional arrays. A thermally-induced alloy-mixing technique is described, which produced a 110 meV carrier confinement energy, together with a refractive index change of -.012, averaged over the 2.6 μm nonlinear medium thickness. The resulting electrical and optical confinement is shown to improve the nonlinear characteristics, by limiting lateral carrier diffusion and light diffraction.

  15. Nonlinear robust hierarchical control for nonlinear uncertain systems

    Directory of Open Access Journals (Sweden)

    Leonessa Alexander

    1999-01-01

    Full Text Available A nonlinear robust control-system design framework predicated on a hierarchical switching controller architecture parameterized over a set of moving nominal system equilibria is developed. Specifically, using equilibria-dependent Lyapunov functions, a hierarchical nonlinear robust control strategy is developed that robustly stabilizes a given nonlinear system over a prescribed range of system uncertainty by robustly stabilizing a collection of nonlinear controlled uncertain subsystems. The robust switching nonlinear controller architecture is designed based on a generalized (lower semicontinuous Lyapunov function obtained by minimizing a potential function over a given switching set induced by the parameterized nominal system equilibria. The proposed framework robustly stabilizes a compact positively invariant set of a given nonlinear uncertain dynamical system with structured parametric uncertainty. Finally, the efficacy of the proposed approach is demonstrated on a jet engine propulsion control problem with uncertain pressure-flow map data.

  16. Nonlinear scattering in plasmonic nanostructures

    Science.gov (United States)

    Chu, Shi-Wei

    2016-09-01

    Nonlinear phenomena provide novel light manipulation capabilities and innovative applications. Recently, we discovered nonlinear saturation on single-particle scattering of gold nanospheres by continuous-wave laser excitation and innovatively applied to improve microscopic resolution down to λ/8. However, the nonlinearity was limited to the green-orange plasmonic band of gold nanosphere, and the underlying mechanism has not yet been fully understood. In this work, we demonstrated that nonlinear scattering exists for various material/geometry combinations, thus expanding the applicable wavelength range. For near-infrared, gold nanorod is used, while for blue-violet, silver nanospheres are adopted. In terms of mechanism, the nonlinearity may originate from interband/intraband absorption, hot electron, or hot lattice, which are spectrally mixed in the case of gold nanosphere. For gold nanorod and silver nanosphere, nonlinear scattering occurs at plasmonic resonances, which are spectrally far from interband/intraband absorptions, so they are excluded. We found that the nonlinear index is much larger than possible contributions from hot electrons in literature. Therefore, we conclude that hot lattice is the major mechanism. In addition, we propose that similar to z-scan, which is the standard method to characterize nonlinearity of a thin sample, laser scanning microscopy should be adopted as the standard method to characterize nonlinearity from a nanostructure. Our work not only provides the physical mechanism of the nonlinear scattering, but also paves the way toward multi-color superresolution imaging based on non-bleaching plasmonic scattering.

  17. Discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities

    DEFF Research Database (Denmark)

    Khare, A.; Rasmussen, Kim Ø; Salerno, M.

    2006-01-01

    A class of discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities is introduced. These equations are derived from the same Hamiltonian using different Poisson brackets and include as particular cases the saturable discrete nonlinear Schrodinger equation and the Ablowi......-Ladik equation. As a common property, these equations possess three kinds of exact analytical stationary solutions for which the Peierls-Nabarro barrier is zero. Several properties of these solutions, including stability, discrete breathers, and moving solutions, are investigated....

  18. Dichromatic nonlinear eigenmodes in slab waveguide with chi(2) nonlinearity.

    Science.gov (United States)

    Darmanyan, S A; Nevière, M

    2001-03-01

    The existence of purely nonlinear eigenmodes in a waveguiding structure composed of a slab with quadratic nonlinearity surrounded by (non)linear claddings is reported. Modes having bright and dark solitonlike shapes and consisting of two mutually locked harmonics are identified. Asymmetrical modes are shown to exist in symmetrical environments. Constraints for the existence of the modes are derived in terms of parameters of guiding structure materials.

  19. Nonlinear Schrodinger equation with chaotic, random, and nonperiodic nonlinearity

    CERN Document Server

    Cardoso, W B; Avelar, A T; Bazeia, D; Hussein, M S

    2009-01-01

    In this paper we deal with a nonlinear Schr\\"{o}dinger equation with chaotic, random, and nonperiodic cubic nonlinearity. Our goal is to study the soliton evolution, with the strength of the nonlinearity perturbed in the space and time coordinates and to check its robustness under these conditions. Comparing with a real system, the perturbation can be related to, e.g., impurities in crystalline structures, or coupling to a thermal reservoir which, on the average, enhances the nonlinearity. We also discuss the relevance of such random perturbations to the dynamics of Bose-Einstein Condensates and their collective excitations and transport.

  20. Nonlinear Optical Rectennas

    CERN Document Server

    Stolz, A; Markey, L; Francs, G Colas des; Bouhelier, A

    2013-01-01

    We introduce strongly-coupled optical gap antennas to interface optical radiation with current-carrying electrons at the nanoscale. The transducer relies on the nonlinear optical and electrical properties of an optical antenna operating in the tunneling regime. We discuss the underlying physical mechanisms controlling the conversion and demonstrate that a two-wire optical antenna can provide advanced optoelectronic functionalities beyond tailoring the electromagnetic response of a single emitter. Interfacing an electronic command layer with a nanoscale optical device may thus be facilitated by the optical rectennas discussed here.

  1. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E

    1991-01-01

    In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are

  2. Nonlinear electrodynamics with birefringence

    CERN Document Server

    Kruglov, S I

    2015-01-01

    A new model of nonlinear electrodynamics with three parameters is suggested. The phenomena of vacuum birefringence takes place when there is the external constant magnetic field. We calculate the indices of refraction for two polarizations of electromagnetic waves, parallel and perpendicular to the magnetic induction field. From the Bir\\'{e}fringence Magn\\'{e}tique du Vide (BMV) experiment one of the coefficients, $\\gamma\\approx 10^{-20}$ T$^{-2}$, was estimated. The canonical, symmetrical Belinfante energy-momentum tensors and dilatation current were obtained. The dilatation symmetry and the dual symmetry are broken in the model considered.

  3. Nonlinear diffusion equations

    CERN Document Server

    Wu Zhuo Qun; Li Hui Lai; Zhao Jun Ning

    2001-01-01

    Nonlinear diffusion equations, an important class of parabolic equations, come from a variety of diffusion phenomena which appear widely in nature. They are suggested as mathematical models of physical problems in many fields, such as filtration, phase transition, biochemistry and dynamics of biological groups. In many cases, the equations possess degeneracy or singularity. The appearance of degeneracy or singularity makes the study more involved and challenging. Many new ideas and methods have been developed to overcome the special difficulties caused by the degeneracy and singularity, which

  4. Nonlinear dynamics in psychology

    Directory of Open Access Journals (Sweden)

    Stephen J. Guastello

    2001-01-01

    Full Text Available This article provides a survey of the applications of nonlinear dynamical systems theory to substantive problems encountered in the full scope of psychological science. Applications are organized into three topical areas – cognitive science, social and organizational psychology, and personality and clinical psychology. Both theoretical and empirical studies are considered with an emphasis on works that capture the broadest scope of issues that are of substantive interest to psychological theory. A budding literature on the implications of NDS principles in professional practice is reported also.

  5. Nonlinear Control Systems

    Science.gov (United States)

    2009-11-18

    analytic semigroup T(t) ~ eAl is exponentially stable (Notice that it is also a contraction semigroup ). 3. Be 3(U, Z) and P e £(W, 2) are bounded. 4. Ce...quite often in practice, .4 is self-adjoint. We also note that, since we assume (—A) is sectorial, we work with the semigroup exp(.4f) rather than...Uniform Output Regulation of Nonlinear Sys- tems: A convergent Dynamics Approach, Birkhauser, Boston, 2006. 23 135] A. Pazy, Semigroups of Linear

  6. Nonlinear elliptic systems

    Directory of Open Access Journals (Sweden)

    DJAIRO G. DEFIGUEIREDO

    2000-12-01

    Full Text Available In this paper we treat the question of the existence of solutions of boundary value problems for systems of nonlinear elliptic equations of the form - deltau = f (x, u, v,Ñu,Ñv, - deltav = g(x, u, v, Ñu, Ñv, in omega, We discuss several classes of such systems using both variational and topological methods. The notion of criticality takes into consideration the coupling, which plays important roles in both a priori estimates for the solutions and Palais-Smale conditions for the associated functional in the variational case.

  7. Global Analysis of Nonlinear Dynamics

    CERN Document Server

    Luo, Albert

    2012-01-01

    Global Analysis of Nonlinear Dynamics collects chapters on recent developments in global analysis of non-linear dynamical systems with a particular emphasis on cell mapping methods developed by Professor C.S. Hsu of the University of California, Berkeley. This collection of contributions prepared by a diverse group of internationally recognized researchers is intended to stimulate interests in global analysis of complex and high-dimensional nonlinear dynamical systems, whose global properties are largely unexplored at this time. This book also: Presents recent developments in global analysis of non-linear dynamical systems Provides in-depth considerations and extensions of cell mapping methods Adopts an inclusive style accessible to non-specialists and graduate students Global Analysis of Nonlinear Dynamics is an ideal reference for the community of nonlinear dynamics in different disciplines including engineering, applied mathematics, meteorology, life science, computational science, and medicine.  

  8. Nonlinear evolution of drift instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.W.; Krommes, J.A.; Oberman, C.R.; Smith, R.A.

    1984-01-01

    The nonlinear evolution of collisionless drift instabilities in a shear-free magnetic field has been studied by means of gyrokinetic particle simulation as well as numerical integration of model mode-coupling equations. The purpose of the investigation is to identify relevant nonlinear mechanisms responsible for the steady-state drift wave fluctuations. It is found that the saturation of the instability is mainly caused by the nonlinear E x B convection of the resonant electrons and their associated velocity space nonlinearity. The latter also induces energy exchange between the competing modes, which, in turn, gives rise to enhanced diffusion. The nonlinear E x B convection of the ions, which contributes to the nonlinear frequency shift, is also an important ingredient for the saturation.

  9. Z-scan theory for nonlocal nonlinear media with simultaneous nonlinear refraction and nonlinear absorption.

    Science.gov (United States)

    Rashidian Vaziri, Mohammad Reza

    2013-07-10

    In this paper, the Z-scan theory for nonlocal nonlinear media has been further developed when nonlinear absorption and nonlinear refraction appear simultaneously. To this end, the nonlinear photoinduced phase shift between the impinging and outgoing Gaussian beams from a nonlocal nonlinear sample has been generalized. It is shown that this kind of phase shift will reduce correctly to its known counterpart for the case of pure refractive nonlinearity. Using this generalized form of phase shift, the basic formulas for closed- and open-aperture beam transmittances in the far field have been provided, and a simple procedure for interpreting the Z-scan results has been proposed. In this procedure, by separately performing open- and closed-aperture Z-scan experiments and using the represented relations for the far-field transmittances, one can measure the nonlinear absorption coefficient and nonlinear index of refraction as well as the order of nonlocality. Theoretically, it is shown that when the absorptive nonlinearity is present in addition to the refractive nonlinearity, the sample nonlocal response can noticeably suppress the peak and enhance the valley of the Z-scan closed-aperture transmittance curves, which is due to the nonlocal action's ability to change the beam transverse dimensions.

  10. Topics on nonlinear generalized functions

    CERN Document Server

    Colombeau, J F

    2011-01-01

    The aim of this paper is to give the text of a recent introduction to nonlinear generalized functions exposed in my talk in the congress gf2011, which was asked by several participants. Three representative topics were presented: two recalls "Nonlinear generalized functions and their connections with distribution theory", "Examples of applications", and a recent development: "Locally convex topologies and compactness: a functional analysis of nonlinear generalized functions".

  11. Nonlinear Ultrasonic Phased Array Imaging

    Science.gov (United States)

    Potter, J. N.; Croxford, A. J.; Wilcox, P. D.

    2014-10-01

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

  12. Nonlinear ultrasonic phased array imaging

    OpenAIRE

    Potter, J N; Croxford, A.J.; Wilcox, P. D.

    2014-01-01

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging t...

  13. Research on Nonlinear Dynamical Systems.

    Science.gov (United States)

    1983-01-10

    investigated fundamental aspects of functional differential equations, including qualitative questions (stability, nonlinear oscillations ), in 142,45,47,52...Bifurcation in the Duffing equation with several parameters, II. Proc. of the Royal Society of Edinburgh, Series A, 79A (1977), pp.317-326. 1I.J (with ;Ibtoas...Lecture Notes in Mathematics, Vol. 730 (1979). [54] Nonlinear oscillations in equations with delays. Proc. at A.M.S. 10th Summer Seminar on Nonlinear

  14. Nonlinear ultrasonic phased array imaging.

    Science.gov (United States)

    Potter, J N; Croxford, A J; Wilcox, P D

    2014-10-03

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

  15. Remote Atmospheric Nonlinear Optical Magnetometry

    Science.gov (United States)

    2014-04-28

    Boyd , Nonlinear Optics (Elsevier, Burlington, MA, 2008). [13] M. Scully and S. Zubairy, Quantum Optics (Cambridge U. Press, Cambridge, UK, 1997...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6703--14-9548 Remote Atmospheric Nonlinear Optical Magnetometry PhilliP SPrangle...b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Remote Atmospheric Nonlinear Optical Magnetometry Phillip Sprangle, Luke

  16. Applications of nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2008-01-01

    * The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The bo

  17. Linearization of conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belendez, A; Alvarez, M L [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E; Pascual, I [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es

    2009-03-11

    A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for the complete range of oscillation amplitudes. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of the technique.

  18. Problems in nonlinear resistive MHD

    Energy Technology Data Exchange (ETDEWEB)

    Turnbull, A.D.; Strait, E.J.; La Haye, R.J.; Chu, M.S.; Miller, R.L. [General Atomics, San Diego, CA (United States)

    1998-12-31

    Two experimentally relevant problems can relatively easily be tackled by nonlinear MHD codes. Both problems require plasma rotation in addition to the nonlinear mode coupling and full geometry already incorporated into the codes, but no additional physics seems to be crucial. These problems discussed here are: (1) nonlinear coupling and interaction of multiple MHD modes near the B limit and (2) nonlinear coupling of the m/n = 1/1 sawtooth mode with higher n gongs and development of seed islands outside q = 1.

  19. Asymptotics for dissipative nonlinear equations

    CERN Document Server

    Hayashi, Nakao; Kaikina, Elena I; Shishmarev, Ilya A

    2006-01-01

    Many of problems of the natural sciences lead to nonlinear partial differential equations. However, only a few of them have succeeded in being solved explicitly. Therefore different methods of qualitative analysis such as the asymptotic methods play a very important role. This is the first book in the world literature giving a systematic development of a general asymptotic theory for nonlinear partial differential equations with dissipation. Many typical well-known equations are considered as examples, such as: nonlinear heat equation, KdVB equation, nonlinear damped wave equation, Landau-Ginzburg equation, Sobolev type equations, systems of equations of Boussinesq, Navier-Stokes and others.

  20. Focus issue introduction: nonlinear optics.

    Science.gov (United States)

    Boulanger, Benoît; Cundiff, Steven T; Gauthier, Daniel J; Karlsson, Magnus; Lu, Yan-Qing; Norwood, Robert A; Skryabin, Dmitry; Taira, Takunori

    2011-11-07

    It is now fifty years since the original observation of second harmonic generation ushered in the field of nonlinear optics, close on the heels of the invention of the laser. This feature issue celebrates this anniversary with papers that span the range from new nonlinear optical materials, through the increasingly novel methods that have been developed for phase matching, to emerging areas such as nonlinear metamaterials and plasmonic enhancement of optical properties. It is clear that the next fifty years of nonlinear optics will witness a proliferation of new applications with increasing technological impact.

  1. Nonlocal homogenization for nonlinear metamaterials

    CERN Document Server

    Gorlach, Maxim A; Lapine, Mikhail; Kivshar, Yuri S; Belov, Pavel A

    2016-01-01

    We present a consistent theoretical approach for calculating effective nonlinear susceptibilities of metamaterials taking into account both frequency and spatial dispersion. Employing the discrete dipole model, we demonstrate that effects of spatial dispersion become especially pronounced in the vicinity of effective permittivity resonance where nonlinear susceptibilities reach their maxima. In that case spatial dispersion may enable simultaneous generation of two harmonic signals with the same frequency and polarization but different wave vectors. We also prove that the derived expressions for nonlinear susceptibilities transform into the known form when spatial dispersion effects are negligible. In addition to revealing new physical phenomena, our results provide useful theoretical tools for analysing resonant nonlinear metamaterials.

  2. Nonlinear Peltier effect in semiconductors

    Science.gov (United States)

    Zebarjadi, Mona; Esfarjani, Keivan; Shakouri, Ali

    2007-09-01

    Nonlinear Peltier coefficient of a doped InGaAs semiconductor is calculated numerically using the Monte Carlo technique. The Peltier coefficient is also obtained analytically for single parabolic band semiconductors assuming a shifted Fermi-Dirac electronic distribution under an applied bias. Analytical results are in agreement with numerical simulations. Key material parameters affecting the nonlinear behavior are doping concentration, effective mass, and electron-phonon coupling. Current density thresholds at which nonlinear behavior is observable are extracted from numerical data. It is shown that the nonlinear Peltier effect can be used to enhance cooling of thin film microrefrigerator devices especially at low temperatures.

  3. Nonlinearities in Behavioral Macroeconomics.

    Science.gov (United States)

    Gomes, Orlando

    2017-07-01

    This article undertakes a journey across the literature on behavioral macroeconomics, with attention concentrated on the nonlinearities that the behavioral approach typically suggests or implies. The emphasis is placed on thinking the macro economy as a living organism, composed of many interacting parts, each one having a will of its own, which is in sharp contrast with the mechanism of the orthodox view (well represented by the neoclassical or new Keynesian dynamic stochastic general equilibrium - DSGE - model). The paper advocates that a thorough understanding of individual behavior in collective contexts is the only possible avenue to further explore macroeconomic phenomena and the often observed 'anomalies' that the benchmark DSGE macro framework is unable to explain or justify. After a reflection on the role of behavioral traits as a fundamental component of a new way of thinking the economy, the article proceeds with a debate on some of the most relevant frameworks in the literature that somehow link macro behavior and nonlinearities; covered subjects include macro models with disequilibrium rules, agent-based models that highlight interaction and complexity, evolutionary switching frameworks, and inattention based decision problems. These subjects have, as a fundamental point in common, the use of behavioral elements to transform existing interpretations of the economic reality, making it more evident how irregular fluctuations emerge and unfold on the aggregate.

  4. Improved nonlinear prediction method

    Science.gov (United States)

    Adenan, Nur Hamiza; Md Noorani, Mohd Salmi

    2014-06-01

    The analysis and prediction of time series data have been addressed by researchers. Many techniques have been developed to be applied in various areas, such as weather forecasting, financial markets and hydrological phenomena involving data that are contaminated by noise. Therefore, various techniques to improve the method have been introduced to analyze and predict time series data. In respect of the importance of analysis and the accuracy of the prediction result, a study was undertaken to test the effectiveness of the improved nonlinear prediction method for data that contain noise. The improved nonlinear prediction method involves the formation of composite serial data based on the successive differences of the time series. Then, the phase space reconstruction was performed on the composite data (one-dimensional) to reconstruct a number of space dimensions. Finally the local linear approximation method was employed to make a prediction based on the phase space. This improved method was tested with data series Logistics that contain 0%, 5%, 10%, 20% and 30% of noise. The results show that by using the improved method, the predictions were found to be in close agreement with the observed ones. The correlation coefficient was close to one when the improved method was applied on data with up to 10% noise. Thus, an improvement to analyze data with noise without involving any noise reduction method was introduced to predict the time series data.

  5. Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available A dynamic model is proposed for a polymer foam-based nonlinear cushioning system. An accurate analytical solution for the nonlinear free vibration of the system is derived by applying He's variational iteration method, and conditions for resonance are obtained, which should be avoided in the cushioning design.

  6. Método Mãe Canguru: aplicação no Brasil, evidências científicas e impacto sobre o aleitamento materno Kangaroo Mother Care: scientific evidences and impact on breastfeeding

    Directory of Open Access Journals (Sweden)

    Sonia Isoyama Venancio

    2004-11-01

    Full Text Available OBJETIVO: Descrever o histórico do Método Mãe Canguru e apresentar evidências científicas sobre os benefícios dessa prática para os bebês de baixo peso no tocante a morbimortalidade, desenvolvimento psicoafetivo, neurossensorial e amamentação. FONTES DE DADOS: Foram consultadas publicações sobre o Método Mãe Canguru abrangendo o período de 1983 até 2004, identificadas nas bases de dados MEDLINE e Lilacs, bem como livros, teses e publicações técnicas do Ministério da Saúde. SÍNTESE DOS DADOS: Desde sua primeira descrição, o Método Mãe Canguru tem sido amplamente estudado. A análise de experimentos randomizados mostrou que o mesmo consiste em fator de proteção para a amamentação exclusiva no momento da alta hospitalar (RR 0,41; IC95% 0,25-0,68. O método também está associado a redução do risco de infecção hospitalar com 41 semanas de idade gestacional corrigida (RR 0,49; IC95% 0,25-0,93; redução de enfermidades graves (RR 0,30; IC95% 0,14-0,67; redução de infecções do trato respiratório inferior aos 6 meses (RR 0,37; IC95% 0,15-0,89; e maior ganho ponderal diário (diferença de médias de 3,6 g/dia; IC95% 0,8-6,4. O desenvolvimento psicomotor foi semelhante entre bebês submetidos ao Método Mãe Canguru e controles aos 12 meses, e não houve evidências de impacto sobre a mortalidade infantil. CONCLUSÃO: Há evidências de impacto positivo do Método Mãe Canguru sobre a prática da amamentação. Embora o método pareça reduzir a morbidade infantil, as evidências são ainda insuficientes para que o mesmo seja recomendado rotineiramente. Por outro lado, não existem relatos sobre efeitos deletérios da aplicação do método. Há a necessidade de se realizar estudos sobre a efetividade, aplicabilidade e aceitabilidade do Método Mãe Canguru em nosso meio.OBJECTIVE: To describe the history of the Kangaroo Mother Care and present scientific evidence about benefits of this practice on morbidity and

  7. Nonlinear Evolution of Ferroelectric Domains

    Institute of Scientific and Technical Information of China (English)

    WeiLU; Dai-NingFANG; 等

    1997-01-01

    The nonlinear evolution of ferroelectric domains is investigated in the paper and amodel is proposed which can be applied to numerical computation.Numerical results show that the model can accurately predict some nonlinear behavior and consist with those experimental results.

  8. Nonlinear Electrodynamics and black holes

    CERN Document Server

    Breton, N; Breton, Nora; Garcia-Salcedo, Ricardo

    2007-01-01

    It is addressed the issue of black holes with nonlinear electromagnetic field, focussing mainly in the Born-Infeld case. The main features of these systems are described, for instance, geodesics, energy conditions, thermodynamics and isolated horizon aspects. Also are revised some black hole solutions of alternative nonlinear electrodynamics and its inconveniences.

  9. Space curves, anholonomy and nonlinearity

    Indian Academy of Sciences (India)

    Radha Balakrishnan

    2005-04-01

    Using classical differential geometry, we discuss the phenomenon of anholonomy that gets associated with a static and a moving curve. We obtain the expressions for the respective geometric phases in the two cases and interpret them. We show that there is a close connection between anholonomy and nonlinearity in a wide class of nonlinear systems.

  10. Balancing for unstable nonlinear systems

    NARCIS (Netherlands)

    Scherpen, J.M.A.

    1993-01-01

    A previously obtained method of balancing for stable nonlinear systems is extended to unstable nonlinear systems. The similarity invariants obtained by the concept of LQG balancing for an unstable linear system can also be obtained by considering a past and future energy function of the system. By c

  11. Nonlinear diffusion and superconducting hysteresis

    Energy Technology Data Exchange (ETDEWEB)

    Mayergoyz, I.D. [Univ. of Maryland, College Park, MD (United States)

    1996-12-31

    Nonlinear diffusion of electromagnetic fields in superconductors with ideal and gradual resistive transitions is studied. Analytical results obtained for linear and nonlinear polarizations of electromagnetic fields are reported. These results lead to various extensions of the critical state model for superconducting hysteresis.

  12. Nonlinear energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Lallart, Mickael; Guyomar, Daniel, E-mail: mickael.lallart@insa-lyon.fr [LGEF, INSA-Lyon, Universite de Lyon, 8 rue de la Physique, F-69621 (France)

    2011-10-29

    The proliferation of wearable and left-behind devices has raised the issue of powering such systems. While primary batteries have been widely used in order to address this issue, recent trends have focused on energy harvesting products that feature high reliability and low maintenance issues. Among all the ambient sources available for energy harvesting, vibrations and heat have been of significant interest among the research community for small-scale devices. However, the conversion abilities of materials are still limited when dealing with systems featuring small dimensions. The purpose of this paper is to presents an up-to-date view of nonlinear approaches for increasing the efficiency of electromechanical and electrocaloric conversion mechanisms. From the modeling of the operation principles of the different architectures, a comparative analysis will be exposed, emphasizing the advantages and drawbacks of the presented concepts, in terms of maximal output power (under constant vibration magnitude or taking into account the damping effect), load independence, and implementation easiness.

  13. Nonlinear organic plasmonics

    CERN Document Server

    Fainberg, B D

    2015-01-01

    Purely organic materials with negative and near-zero dielectric permittivity can be easily fabricated. Here we develop a theory of nonlinear non-steady-state organic plasmonics with strong laser pulses. The bistability response of the electron-vibrational model of organic materials in the condensed phase has been demonstrated. Non-steady-state organic plasmonics enable us to obtain near-zero dielectric permittivity during a short time. We have proposed to use non-steady-state organic plasmonics for the enhancement of intersite dipolar energy-transfer interaction in the quantum dot wire that influences on electron transport through nanojunctions. Such interactions can compensate Coulomb repulsions for particular conditions. We propose the exciton control of Coulomb blocking in the quantum dot wire based on the non-steady-state near-zero dielectric permittivity of the organic host medium.

  14. Nonlinear Water Waves

    CERN Document Server

    2016-01-01

    This volume brings together four lecture courses on modern aspects of water waves. The intention, through the lectures, is to present quite a range of mathematical ideas, primarily to show what is possible and what, currently, is of particular interest. Water waves of large amplitude can only be fully understood in terms of nonlinear effects, linear theory being not adequate for their description. Taking advantage of insights from physical observation, experimental evidence and numerical simulations, classical and modern mathematical approaches can be used to gain insight into their dynamics. The book presents several avenues and offers a wide range of material of current interest. Due to the interdisciplinary nature of the subject, the book should be of interest to mathematicians (pure and applied), physicists and engineers. The lectures provide a useful source for those who want to begin to investigate how mathematics can be used to improve our understanding of water wave phenomena. In addition, some of the...

  15. Nonlinear estimation and classification

    CERN Document Server

    Hansen, Mark; Holmes, Christopher; Mallick, Bani; Yu, Bin

    2003-01-01

    Researchers in many disciplines face the formidable task of analyzing massive amounts of high-dimensional and highly-structured data This is due in part to recent advances in data collection and computing technologies As a result, fundamental statistical research is being undertaken in a variety of different fields Driven by the complexity of these new problems, and fueled by the explosion of available computer power, highly adaptive, non-linear procedures are now essential components of modern "data analysis," a term that we liberally interpret to include speech and pattern recognition, classification, data compression and signal processing The development of new, flexible methods combines advances from many sources, including approximation theory, numerical analysis, machine learning, signal processing and statistics The proposed workshop intends to bring together eminent experts from these fields in order to exchange ideas and forge directions for the future

  16. Nonlinear transmission sputtering

    Science.gov (United States)

    Bitensky, I. S.; Sigmund, P.

    1996-05-01

    General expressions have been derived for the nonlinear yield of transmission sputtering for an incident polyatomic ion under the assumption that the molecule breaks up on entering the target and that sputter yields are enhanced due to proximity of atomic trajectories. Special attention is given to the case of negligible Coulomb explosion where projectile atoms penetrate independently. For weakly overlapping trajectories, the yield enhancement factor of a polyatomic molecule can be expressed by that of a diatom, amended with a correction for triple correlations if necessary. This expression is in good agreement with recent experimental findings on phenylalanine targets. Pertinent results on multiple scattering of atomic ions are reviewed and applied to independently-moving fragment atoms. The merits of measurements at variable layer thickness in addition to variable projectile energy are mentioned.

  17. Perspectives on Nonlinear Filtering

    KAUST Repository

    Law, Kody

    2015-01-07

    The solution to the problem of nonlinear filtering may be given either as an estimate of the signal (and ideally some measure of concentration), or as a full posterior distribution. Similarly, one may evaluate the fidelity of the filter either by its ability to track the signal or its proximity to the posterior filtering distribution. Hence, the field enjoys a lively symbiosis between probability and control theory, and there are plenty of applications which benefit from algorithmic advances, from signal processing, to econometrics, to large-scale ocean, atmosphere, and climate modeling. This talk will survey some recent theoretical results involving accurate signal tracking with noise-free (degenerate) dynamics in high-dimensions (infinite, in principle, but say d between 103 and 108 , depending on the size of your application and your computer), and high-fidelity approximations of the filtering distribution in low dimensions (say d between 1 and several 10s).

  18. Nonlinear rotordynamics analysis

    Science.gov (United States)

    Day, W. B.; Zalik, R. A.

    1986-01-01

    Three analytic consequences of the nonlinear Jeffcott equations are examined. The primary application of these analyses is directed toward understanding the excessive vibrations recorded in the Liquid Oxygen (LOX) pump of the Space Shuttle Main Engine (SSME) during hot firing ground testing. The first task is to provide bounds on the coefficients of the equations which delimit the two cases of numerical solution as a circle or an annulus. The second task examines the mathematical generalization to multiple forcing functions, which includes the special problems of mass imbalance, side force, rubbing, and combination of these forces. Finally, stability and boundedness of the steady-state solutions is discussed and related to the corresponding linear problem.

  19. Nonlinearities in vegetation functioning

    Science.gov (United States)

    Ceballos-Núñez, Verónika; Müller, Markus; Metzler, Holger; Sierra, Carlos

    2016-04-01

    Given the current drastic changes in climate and atmospheric CO2 concentrations, and the role of vegetation in the global carbon cycle, there is increasing attention to the carbon allocation component in biosphere terrestrial models. Improving the representation of C allocation in models could be the key to having better predictions of the fate of C once it enters the vegetation and is partitioned to C pools of different residence times. C allocation has often been modeled using systems of ordinary differential equations, and it has been hypothesized that most models can be generalized with a specific form of a linear dynamical system. However, several studies have highlighted discrepancies between empirical observations and model predictions, attributing these differences to problems with model structure. Although efforts have been made to compare different models, the outcome of these qualitative assessments has been a conceptual categorization of them. In this contribution, we introduce a new effort to identify the main properties of groups of models by studying their mathematical structure. For this purpose, we performed a literature research of the relevant models of carbon allocation in vegetation and developed a database with their representation in symbolic mathematics. We used the Python package SymPy for symbolic mathematics as a common language and manipulated the models to calculate their Jacobian matrix at fixed points and their eigenvalues, among other mathematical analyses. Our preliminary results show a tendency of inverse proportionality between model complexity and size of time/space scale; complex interactions between the variables controlling carbon allocation in vegetation tend to operate at shorter time/space scales, and vice-versa. Most importantly, we found that although the linear structure is common, other structures with non-linearities have been also proposed. We, therefore, propose a new General Model that can accommodate these

  20. Nonlinear field space cosmology

    Science.gov (United States)

    Mielczarek, Jakub; Trześniewski, Tomasz

    2017-08-01

    We consider the FRW cosmological model in which the matter content of the Universe (playing the role of an inflaton or quintessence) is given by a novel generalization of the massive scalar field. The latter is a scalar version of the recently introduced nonlinear field space theory, where the physical phase space of a given field is assumed to be compactified at large energies. For our analysis, we choose the simple case of a field with the spherical phase space and endow it with the generalized Hamiltonian analogous to the XXZ Heisenberg model, normally describing a system of spins in condensed matter physics. Subsequently, we study both the homogenous cosmological sector and linear perturbations of such a test field. In the homogenous sector, we find that nonlinearity of the field phase space is becoming relevant for large volumes of the Universe and can lead to a recollapse, and possibly also at very high energies, leading to the phase of a bounce. Quantization of the field is performed in the limit where the nontrivial nature of its phase space can be neglected, while there is a nonvanishing contribution from the Lorentz symmetry breaking term of the Hamiltonian. As a result, in the leading order of the XXZ anisotropy parameter, we find that the inflationary spectral index remains unmodified with respect to the standard case but the total amplitude of perturbations is subject to a correction. The Bunch-Davies vacuum state also becomes appropriately corrected. The proposed new approach is bringing cosmology and condensed matter physics closer together, which may turn out to be beneficial for both disciplines.

  1. NONLINEAR STABILITY FOR EADY'S MODEL

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-ming; QIU Ling-cun

    2005-01-01

    Poincaré type integral inequality plays an important role in the study of nonlinear stability ( in the sense of Arnold's second theorem) for three-dimensional quasigeostophic flow. The nonlinear stability of Eady's model is one of the most important cases in the application of the method. But the best nonlinear stability criterion obtained so far and the linear stability criterion are not coincident. The two criteria coincide only when the period of the channel is infinite.additional conservation law of momentum and by rigorous estimate of integral inequality. So the new nonlinear stability criterion was obtained, which shows that for Eady 's model in the periodic channel, the linear stable implies the nonlinear stable.

  2. Nonlinear Waves in Complex Systems

    DEFF Research Database (Denmark)

    2007-01-01

    The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations, it is the ......The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations......, it is the universality and robustness of the main models with respect to perturbations that developped the field. This is true for both continuous and discrete equations. In this volume we keep this broad view and draw new perspectives for nonlinear waves in complex systems. In particular we address energy flow...

  3. Terahertz Nonlinearity in Graphene Plasmons

    CERN Document Server

    Jadidi, Mohammad M; Winnerl, Stephan; Sushkov, Andrei B; Drew, H Dennis; Murphy, Thomas E; Mittendorff, Martin

    2015-01-01

    Sub-wavelength graphene structures support localized plasmonic resonances in the terahertz and mid-infrared spectral regimes. The strong field confinement at the resonant frequency is predicted to significantly enhance the light-graphene interaction, which could enable nonlinear optics at low intensity in atomically thin, sub-wavelength devices. To date, the nonlinear response of graphene plasmons and their energy loss dynamics have not been experimentally studied. We measure and theoretically model the terahertz nonlinear response and energy relaxation dynamics of plasmons in graphene nanoribbons. We employ a THz pump-THz probe technique at the plasmon frequency and observe a strong saturation of plasmon absorption followed by a 10 ps relaxation time. The observed nonlinearity is enhanced by two orders of magnitude compared to unpatterned graphene with no plasmon resonance. We further present a thermal model for the nonlinear plasmonic absorption that supports the experimental results.

  4. Fast Numerical Nonlinear Fourier Transforms

    CERN Document Server

    Wahls, Sander

    2014-01-01

    The nonlinear Fourier transform, which is also known as the forward scattering transform, decomposes a periodic signal into nonlinearly interacting waves. In contrast to the common Fourier transform, these waves no longer have to be sinusoidal. Physically relevant waveforms are often available for the analysis instead. The details of the transform depend on the waveforms underlying the analysis, which in turn are specified through the implicit assumption that the signal is governed by a certain evolution equation. For example, water waves generated by the Korteweg-de Vries equation can be expressed in terms of cnoidal waves. Light waves in optical fiber governed by the nonlinear Schr\\"dinger equation (NSE) are another example. Nonlinear analogs of classic problems such as spectral analysis and filtering arise in many applications, with information transmission in optical fiber, as proposed by Yousefi and Kschischang, being a very recent one. The nonlinear Fourier transform is eminently suited to address them ...

  5. Properties of Nonlinear Dynamo Waves

    Science.gov (United States)

    Tobias, S. M.

    1997-01-01

    Dynamo theory offers the most promising explanation of the generation of the sun's magnetic cycle. Mean field electrodynamics has provided the platform for linear and nonlinear models of solar dynamos. However, the nonlinearities included are (necessarily) arbitrarily imposed in these models. This paper conducts a systematic survey of the role of nonlinearities in the dynamo process, by considering the behaviour of dynamo waves in the nonlinear regime. It is demonstrated that only by considering realistic nonlinearities that are non-local in space and time can modulation of the basic dynamo wave he achieved. Moreover, this modulation is greatest when there is a large separation of timescales provided by including a low magnetic Prandtl number in the equation for the velocity perturbations.

  6. Cubication of conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belendez, Augusto; Alvarez, Mariela L [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, Elena; Pascual, Inmaculada [Departamento de Optica, FarmacologIa y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es

    2009-09-15

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.

  7. Nonlinear Oscillators in Space Physics

    Science.gov (United States)

    Lester,Daniel; Thronson, Harley

    2011-01-01

    We discuss dynamical systems that produce an oscillation without an external time dependent source. Numerical results are presented for nonlinear oscillators in the Em1h's atmosphere, foremost the quasi-biennial oscillation (QBOl. These fluid dynamical oscillators, like the solar dynamo, have in common that one of the variables in a governing equation is strongly nonlinear and that the nonlinearity, to first order, has particular form. of 3rd or odd power. It is shown that this form of nonlinearity can produce the fundamental li'equency of the internal oscillation. which has a period that is favored by the dynamical condition of the fluid. The fundamental frequency maintains the oscillation, with no energy input to the system at that particular frequency. Nonlinearities of 2nd or even power could not maintain the oscillation.

  8. Asymptotic expansions in nonlinear rotordynamics

    Science.gov (United States)

    Day, William B.

    1987-01-01

    This paper is an examination of special nonlinearities of the Jeffcott equations in rotordynamics. The immediate application of this analysis is directed toward understanding the excessive vibrations recorded in the LOX pump of the SSME during hot-firing ground testing. Deadband, side force, and rubbing are three possible sources of inducing nonlinearity in the Jeffcott equations. The present analysis initially reduces these problems to the same mathematical description. A special frequency, named the nonlinear natural frequency, is defined and used to develop the solutions of the nonlinear Jeffcott equations as singular asymptotic expansions. This nonlinear natural frequency, which is the ratio of the cross-stiffness and the damping, plays a major role in determining response frequencies.

  9. Nonlinear hyperbolic waves in multidimensions

    CERN Document Server

    Prasad, Phoolan

    2001-01-01

    The propagation of curved, nonlinear wavefronts and shock fronts are very complex phenomena. Since the 1993 publication of his work Propagation of a Curved Shock and Nonlinear Ray Theory, author Phoolan Prasad and his research group have made significant advances in the underlying theory of these phenomena. This volume presents their results and provides a self-contained account and gradual development of mathematical methods for studying successive positions of these fronts.Nonlinear Hyperbolic Waves in Multidimensions includes all introductory material on nonlinear hyperbolic waves and the theory of shock waves. The author derives the ray theory for a nonlinear wavefront, discusses kink phenomena, and develops a new theory for plane and curved shock propagation. He also derives a full set of conservation laws for a front propagating in two space dimensions, and uses these laws to obtain successive positions of a front with kinks. The treatment includes examples of the theory applied to converging wavefronts...

  10. Analysis of Nonlinear Electromagnetic Metamaterials

    CERN Document Server

    Poutrina, Ekaterina; Smith, David R

    2010-01-01

    We analyze the properties of a nonlinear metamaterial formed by integrating nonlinear components or materials into the capacitive regions of metamaterial elements. A straightforward homogenization procedure leads to general expressions for the nonlinear susceptibilities of the composite metamaterial medium. The expressions are convenient, as they enable inhomogeneous system of scattering elements to be described as a continuous medium using the standard notation of nonlinear optics. We illustrate the validity and accuracy of our theoretical framework by performing measurements on a fabricated metamaterial sample composed of an array of split ring resonators (SRRs) with packaged varactors embedded in the capacitive gaps in a manner similar to that of Wang et al. [Opt. Express 16, 16058 (2008)]. Because the SRRs exhibit a predominant magnetic response to electromagnetic fields, the varactor-loaded SRR composite can be described as a magnetic material with nonlinear terms in its effective magnetic susceptibility...

  11. The Nonlinear Analytical Envelope Equation in quadratic nonlinear crystals

    CERN Document Server

    Bache, Morten

    2016-01-01

    We here derive the so-called Nonlinear Analytical Envelope Equation (NAEE) inspired by the work of Conforti et al. [M. Conforti, A. Marini, T. X. Tran, D. Faccio, and F. Biancalana, "Interaction between optical fields and their conjugates in nonlinear media," Opt. Express 21, 31239-31252 (2013)], whose notation we follow. We present a complete model that includes $\\chi^{(2)}$ terms [M. Conforti, F. Baronio, and C. De Angelis, "Nonlinear envelope equation for broadband optical pulses in quadratic media," Phys. Rev. A 81, 053841 (2010)], $\\chi^{(3)}$ terms, and then extend the model to delayed Raman effects in the $\\chi^{(3)}$ term. We therefore get a complete model for ultrafast pulse propagation in quadratic nonlinear crystals similar to the Nonlinear Wave Equation in Frequency domain [H. Guo, X. Zeng, B. Zhou, and M. Bache, "Nonlinear wave equation in frequency domain: accurate modeling of ultrafast interaction in anisotropic nonlinear media," J. Opt. Soc. Am. B 30, 494-504 (2013)], but where the envelope is...

  12. Breatherlike impurity modes in discrete nonlinear lattices

    DEFF Research Database (Denmark)

    Hennig, D.; Rasmussen, Kim; Tsironis, G. P.

    1995-01-01

    We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...

  13. Spatial solitons in nonlinear photonic crystals

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2000-01-01

    We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero.......We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero....

  14. 考虑尾巴的六刚体仿袋鼠跳跃机器人的落地稳定性研究%Stance Stability of a Hopping Robot Based on the Six-rigid-body Kangaroo Model Considering Its Tail

    Institute of Scientific and Technical Information of China (English)

    姜兴长; 杨方; 葛文杰; 杨静

    2011-01-01

    根据袋鼠的生物结构及跳跃的特点,建立了具有尾巴和脚趾的仿袋鼠跳跃机器人六刚体模型。应用拉格朗日方法,建立了机构在着地阶段的运动学和动力学方程。运用Matlab7.0对机器人进行仿真计算分析,给出了机器人在着地阶段的各关节转角、关节驱动力矩、质心轨迹、着地压力和ZMP随时间的变化规律。仿真结果表明:考虑尾巴的六刚体仿袋鼠跳跃机器人能显著提高机构的落地稳定性。%Bsaed on the bionic structure and the motion feature of a kangaroo, we estamlsn a mouel ior unlpeu hopping mechanism of a six-rigid-body bionic kangaroo with tail and toe. We adopt Lagrange method to establish the dynamics and kinematics equations for its stance phase. Taking the hopping robot with parameters as an example and using Matlab 7.0 for simulation ,we obtain the changing rule of each joint angle ,joint driving torque, the centroid trajectory, the ground pressure and ZMP with time of the stance phase. The result shows that the tail can greatly improve the stance stability of the bionic kangaroo robot.

  15. Resource Letter NO-1: Nonlinear Optics

    Science.gov (United States)

    Garmire, Elsa

    2011-03-01

    This Resource Letter provides a guide to the literature on nonlinear optics. Books, journals, and websites are introduced that cover the general subject. Journal articles and websites are cited covering the following topics: second-order nonlinearities in transparent media including second-harmonic generation and optical parametric oscillation, third-order and higher nonlinearities, nonlinear refractive index, absorptive nonlinearities such as saturable absorption and multiphoton absorption, and scattering nonlinearities such as stimulated Raman scattering and stimulated Brillouin scattering. Steady-state and transient phenomena, fiber optics, solitons, nonlinear wave mixing, optical phase conjugation, nonlinear spectroscopy, and multiphoton microscopy are all outlined.

  16. Neurodynamics: nonlinear dynamics and neurobiology.

    Science.gov (United States)

    Abarbanel, H D; Rabinovich, M I

    2001-08-01

    The use of methods from contemporary nonlinear dynamics in studying neurobiology has been rather limited.Yet, nonlinear dynamics has become a practical tool for analyzing data and verifying models. This has led to productive coupling of nonlinear dynamics with experiments in neurobiology in which the neural circuits are forced with constant stimuli, with slowly varying stimuli, with periodic stimuli, and with more complex information-bearing stimuli. Analysis of these more complex stimuli of neural circuits goes to the heart of how one is to understand the encoding and transmission of information by nervous systems.

  17. Dissipative Nonlinear Dynamics in Holography

    CERN Document Server

    Basu, Pallab

    2013-01-01

    We look at the response of a nonlinearly coupled scalar field in an asymptotically AdS black brane geometry and find a behaviour very similar to that of known dissipative nonlinear systems like the chaotic pendulum. Transition to chaos proceeds through a series of period-doubling bifurcations. The presence of dissipation, crucial to this behaviour, arises naturally in a black hole background from the ingoing conditions imposed at the horizon. AdS/CFT translates our solution to a chaotic response of the operator dual to the scalar field. Our setup can also be used to study quench-like behaviour in strongly coupled nonlinear systems.

  18. Acoustic-gravity nonlinear structures

    Directory of Open Access Journals (Sweden)

    D. Jovanović

    2002-01-01

    Full Text Available A catalogue of nonlinear vortex structures associated with acoustic-gravity perturbations in the Earth's atmosphere is presented. Besides the previously known Kelvin-Stewart cat's eyes, dipolar and tripolar structures, new solutions having the form of a row of counter-rotating vortices, and several weakly two-dimensional vortex chains are given. The existence conditions for these nonlinear structures are discussed with respect to the presence of inhomogeneities of the shear flows. The mode-coupling mechanism for the nonlinear generation of shear flows in the presence of linearly unstable acoustic-gravity waves, possibly also leading to intermittency and chaos, is presented.

  19. Nonlinear effects in Thomson backscattering

    Science.gov (United States)

    Maroli, C.; Petrillo, V.; Tomassini, P.; Serafini, L.

    2013-03-01

    We analyze the nonlinear classical effects of the X/γ radiation produced by Thomson/Compton sources. We confirm the development of spectral fringes of the radiation on axis, which comports broadening, shift, and deformation of the spectrum. For the nominal parameters of the SPARC-LAB Thomson scattering and of the European Proposal for the gamma source ELI-NP, however, the radiation, when collected in the suitable acceptance angle, does not reveal many differences from that predicted by the linear model and the nonlinear redshift is subdominant with respect to the quantum recoil. An experiment aimed to the study of the nonlinearities is proposed on the SPARC-LAB source.

  20. Nonlinear Dynamic Phenomena in Mechanics

    CERN Document Server

    Warminski, Jerzy; Cartmell, Matthew P

    2012-01-01

    Nonlinear phenomena should play a crucial role in the design and control of engineering systems and structures as they can drastically change the prevailing dynamical responses. This book covers theoretical and applications-based problems of nonlinear dynamics concerned with both discrete and continuous systems of interest in civil and mechanical engineering. They include pendulum-like systems, slender footbridges, shape memory alloys, sagged elastic cables and non-smooth problems. Pendulums can be used as a dynamic absorber mounted in high buildings, bridges or chimneys. Geometrical nonlinear

  1. Nonlinear Optics: Principles and Applications

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Tidemand-Lichtenberg, Peter

    As nonlinear optics further develops as a field of research in electromagnetic wave propagation, its state-of-the-art technologies will continue to strongly impact real-world applications in a variety of fields useful to the practicing scientist and engineer. From basic principles to examples...... of applications, Nonlinear Optics: Principles and Applications effectively bridges physics and mathematics with relevant applied material for real-world use. The book progresses naturally from fundamental aspects to illustrative examples, and presents a strong theoretical foundation that equips the reader...... and matter, this text focuses on the physical understanding of nonlinear optics, and explores optical material response functions in the time and frequency domain....

  2. Oscillating solitons in nonlinear optics

    Indian Academy of Sciences (India)

    Lin Xiao-Gang; Liu Wen-Jun; Lei Ming

    2016-03-01

    Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota’s bilinear method. The bilinear forms and analytic soliton solutions are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers.

  3. Nonlinear dynamics: Challenges and perspectives

    Indian Academy of Sciences (India)

    M Lakshmanan

    2005-04-01

    The study of nonlinear dynamics has been an active area of research since 1960s, after certain path-breaking discoveries, leading to the concepts of solitons, integrability, bifurcations, chaos and spatio-temporal patterns, to name a few. Several new techniques and methods have been developed to understand nonlinear systems at different levels. Along with these, a multitude of potential applications of nonlinear dynamics have also been enunciated. In spite of these developments, several challenges, some of them fundamental and others on the efficacy of these methods in developing cutting edge technologies, remain to be tackled. In this article, a brief personal perspective of these issues is presented.

  4. Femtosecond nonlinear polarization evolution based on cascade quadratic nonlinearities.

    Science.gov (United States)

    Liu, X; Ilday, F O; Beckwitt, K; Wise, F W

    2000-09-15

    We experimentally demonstrate that one can exploit nonlinear phase shifts produced in type I phase-mismatched second-harmonic generation to produce intensity-dependent polarization evolution with 100-fs pulses. An amplitude modulator based on nonlinear polarization rotation provides passive amplitude-modulation depth of up to ~50%. Applications of the amplitude and phase modulations to mode locking of femtosecond bulk and fiber lasers are promising and are discussed.

  5. Intrinsic nonlinear response of surface plasmon polaritons

    CERN Document Server

    Im, Song-Jin; Kim, Gum-Hyok

    2015-01-01

    We offer a model to describe the intrinsic nonlinear response of surface plasmon polaritons (SPPs). Relation of the complex nonlinear coefficient of SPPs to the third-order nonlinear susceptibility of the metal is provided. As reported in a recent study, gold is highly lossy and simultaneously highly nonlinear due to interband absorption and interband thermo-modulation at a wavelength shorter than 700 nm. The effect of the high loss of the metal on the SPP nonlinear propagation is taken into account in our model. With the model we show difference in sign of real and imaginary parts between the nonlinear propagation coefficient and the nonlinear susceptibility of component material for the first time to our knowledge. Our model could have practical importance in studying plasmonic devices utilizing the nonlinear phase modulation and the nonlinear absorption of SPPs. For example, it allows one to extract the complex nonlinear susceptibility of gold through a measurement of SPP nonlinear propagation at the visib...

  6. Nonlinear functional analysis

    CERN Document Server

    Deimling, Klaus

    1985-01-01

    topics. However, only a modest preliminary knowledge is needed. In the first chapter, where we introduce an important topological concept, the so-called topological degree for continuous maps from subsets ofRn into Rn, you need not know anything about functional analysis. Starting with Chapter 2, where infinite dimensions first appear, one should be familiar with the essential step of consider­ ing a sequence or a function of some sort as a point in the corresponding vector space of all such sequences or functions, whenever this abstraction is worthwhile. One should also work out the things which are proved in § 7 and accept certain basic principles of linear functional analysis quoted there for easier references, until they are applied in later chapters. In other words, even the 'completely linear' sections which we have included for your convenience serve only as a vehicle for progress in nonlinearity. Another point that makes the text introductory is the use of an essentially uniform mathematical languag...

  7. Guidance of Nonlinear Systems

    Science.gov (United States)

    Meyer, George

    1997-01-01

    The paper describes a method for guiding a dynamic system through a given set of points. The paradigm is a fully automatic aircraft subject to air traffic control (ATC). The ATC provides a sequence of way points through which the aircraft trajectory must pass. The way points typically specify time, position, and velocity. The guidance problem is to synthesize a system state trajectory which satisfies both the ATC and aircraft constraints. Complications arise because the controlled process is multi-dimensional, multi-axis, nonlinear, highly coupled, and the state space is not flat. In addition, there is a multitude of possible operating modes, which may number in the hundreds. Each such mode defines a distinct state space model of the process by specifying the state space coordinatization, the partition of the controls into active controls and configuration controls, and the output map. Furthermore, mode transitions must be smooth. The guidance algorithm is based on the inversion of the pure feedback approximations, which is followed by iterative corrections for the effects of zero dynamics. The paper describes the structure and modules of the algorithm, and the performance is illustrated by several example aircraft maneuvers.

  8. Optically nonlinear materials

    CERN Document Server

    Whittam, A J

    2001-01-01

    susceptibility from 26 pm/V (same film without octadecanoic acid) to 40 pm/V. This increase in the second-order susceptibility occurred even though the amount of NLO-active dye was effectively diluted by the addition of the inactive octadecanoic acid. The wavelength of the absorption maximum ranged from 346-440 nm and there was direct correlation between the susceptibilities and the transparency of the films at the harmonic wavelength. Hemicyanine dyes were synthesised, with the general formulae: - (a) C sub 1 sub 8 H sub 3 sub 7 -A sup + -[CH=CH-C sub 6 H sub 4] sub x -N(CH sub 3) sub 2 I (b) C sub 1 sub 8 H sub 3 sub 7 -A sup + -[CH=CH] sub y -C sub 6 H sub 4 -N(CH sub 3) sub 2 I where A sup + is a pyridinium or isoquinolinium acceptor, and x = 1 or 2, and y = 1 or 2. The optically nonlinear dyes were investigated via the Langmuir-Blodgett (LB) technique. The dyes all produced isotherm data, with molecular areas of 22-60 A sup 2 per molecule, which are consistent with the cross-sectional areas of the chromo...

  9. Nonlinear helical MHD instability

    Energy Technology Data Exchange (ETDEWEB)

    Zueva, N.M.; Solov' ev, L.S.

    1977-07-01

    An examination is made of the boundary problem on the development of MHD instability in a toroidal plasma. Two types of local helical instability are noted - Alfven and thermal, and the corresponding criteria of instability are cited. An evaluation is made of the maximum attainable kinetic energy, limited by the degree to which the law of conservation is fulfilled. An examination is made of a precise solution to a kinematic problem on the helical evolution of a cylindrical magnetic configuration at a given velocity distribution in a plasma. A numerical computation of the development of MHD instability in a plasma cylinder by a computerized solution of MHD equations is made where the process's helical symmetry is conserved. The development of instability is of a resonance nature. The instability involves the entire cross section of the plasma and leads to an inside-out reversal of the magnetic surfaces when there is a maximum unstable equilibrium configuration in the nonlinear stage. The examined instability in the tore is apparently stabilized by a magnetic hole when certain limitations are placed on the distribution of flows in the plasma. 29 references, 8 figures.

  10. Design with Nonlinear Constraints

    KAUST Repository

    Tang, Chengcheng

    2015-12-10

    Most modern industrial and architectural designs need to satisfy the requirements of their targeted performance and respect the limitations of available fabrication technologies. At the same time, they should reflect the artistic considerations and personal taste of the designers, which cannot be simply formulated as optimization goals with single best solutions. This thesis aims at a general, flexible yet e cient computational framework for interactive creation, exploration and discovery of serviceable, constructible, and stylish designs. By formulating nonlinear engineering considerations as linear or quadratic expressions by introducing auxiliary variables, the constrained space could be e ciently accessed by the proposed algorithm Guided Projection, with the guidance of aesthetic formulations. The approach is introduced through applications in different scenarios, its effectiveness is demonstrated by examples that were difficult or even impossible to be computationally designed before. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application is extended to developable surfaces including origami with curved creases. Finally, general approaches to extend hard constraints and soft energies are discussed, followed by a concluding remark outlooking possible future studies.

  11. Assessment of fibrotic liver disease with multimodal nonlinear optical microscopy

    Science.gov (United States)

    Lu, Fake; Zheng, Wei; Tai, Dean C. S.; Lin, Jian; Yu, Hanry; Huang, Zhiwei

    2010-02-01

    Liver fibrosis is the excessive accumulation of extracellular matrix proteins such as collagens, which may result in cirrhosis, liver failure, and portal hypertension. In this study, we apply a multimodal nonlinear optical microscopy platform developed to investigate the fibrotic liver diseases in rat models established by performing bile duct ligation (BDL) surgery. The three nonlinear microscopy imaging modalities are implemented on the same sectioned tissues of diseased model sequentially: i.e., second harmonic generation (SHG) imaging quantifies the contents of the collagens, the two-photon excitation fluorescence (TPEF) imaging reveals the morphology of hepatic cells, while coherent anti-Stokes Raman scattering (CARS) imaging maps the distributions of fats or lipids quantitatively across the tissue. Our imaging results show that during the development of liver fibrosis (collagens) in BDL model, fatty liver disease also occurs. The aggregated concentrations of collagen and fat constituents in liver fibrosis model show a certain correlationship between each other.

  12. Nonlinear plasmonics at high temperatures

    Directory of Open Access Journals (Sweden)

    Sivan Yonatan

    2017-01-01

    Full Text Available We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  13. Nonlinear optics and organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.R.

    1994-07-01

    We shall consider an interesting topic relating nonlinear optics and organic materials: how nonlinear optics can be used to study organic materials. One of the main differences between linear and nonlinear responses of a medium to incoming radiation is in their symmetries. It leads to the possibility that some properties of the medium could be more sensitively probed by nonlinear, rather than linear, optical means, or vise versa. A well-known example is that some vibrational modes of a medium could be Raman-active but infrared-inactive, and would be more readily observed by Raman scattering, which is a two-photon transition process. In this paper, we shall discuss, with the help of three examples, how we can use second harmonic generation (SHG) and sum frequency generation (SFG) to obtain unique information about a material. We shall focus on thin films, surfaces, and interfaces.

  14. Nonlinear plasmonics at high temperatures

    Science.gov (United States)

    Sivan, Yonatan; Chu, Shi-Wei

    2017-01-01

    We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  15. Nonlinear microstructured polymer optical fibres

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    . The combination of a small core size and zero-dispersion wavelength at the operating wavelength of widely available femtosecond Ti:sapphire lasers led to an extensive research in supercontinuum generation and other nonlinear effects in PCFs. It is crucial for the efficiency of many nonlinear mechanisms...... that the pump laser wavelength is close to the zero-dispersion wavelength and that the core size is small. Recently, work in fabricating PCFs from materials other than silica has intensified. One of the advantages of using alternative materials can be a higher inherent material nonlinearity, which...... to accurately obtain a small core size while maintaining small structural variations during fibre drawing. This talk will give a presentation of how the mPOFs are fabricated and the route to obtaining nonlinear effects in them....

  16. Device Applications of Nonlinear Dynamics

    CERN Document Server

    Baglio, Salvatore

    2006-01-01

    This edited book is devoted specifically to the applications of complex nonlinear dynamic phenomena to real systems and device applications. While in the past decades there has been significant progress in the theory of nonlinear phenomena under an assortment of system boundary conditions and preparations, there exist comparatively few devices that actually take this rich behavior into account. "Device Applications of Nonlinear Dynamics" applies and exploits this knowledge to make devices which operate more efficiently and cheaply, while affording the promise of much better performance. Given the current explosion of ideas in areas as diverse as molecular motors, nonlinear filtering theory, noise-enhanced propagation, stochastic resonance and networked systems, the time is right to integrate the progress of complex systems research into real devices.

  17. Nonlinear Inflaton Fragmentation after Preheating

    CERN Document Server

    Felder, G N; Felder, Gary N.; Kofman, Lev

    2007-01-01

    We consider the nonlinear dynamics of inflaton fragmentation during and after preheating in the simplest model of chaotic inflation. While the earlier regime of parametric resonant particle production and the later turbulent regime of interacting fields evolving towards equilibrium are well identified and understood, the short intermediate stage of violent nonlinear dynamics remains less explored. Lattice simulations of fully nonlinear preheating dynamics show specific features of this intermediate stage: occupation numbers of the scalar particles are peaked, scalar fields become significantly non-gaussian and the field dynamics become chaotic and irreversible. Visualization of the field dynamics in configuration space reveals that nonlinear interactions generate non-gaussian inflaton inhomogeneities with very fast growing amplitudes. The peaks of the inflaton inhomogeneities coincide with the peaks of the scalar field(s) produced by parametric resonance. When the inflaton peaks reach their maxima, they stop ...

  18. Reconstruction of nonlinear wave propagation

    Science.gov (United States)

    Fleischer, Jason W; Barsi, Christopher; Wan, Wenjie

    2013-04-23

    Disclosed are systems and methods for characterizing a nonlinear propagation environment by numerically propagating a measured output waveform resulting from a known input waveform. The numerical propagation reconstructs the input waveform, and in the process, the nonlinear environment is characterized. In certain embodiments, knowledge of the characterized nonlinear environment facilitates determination of an unknown input based on a measured output. Similarly, knowledge of the characterized nonlinear environment also facilitates formation of a desired output based on a configurable input. In both situations, the input thus characterized and the output thus obtained include features that would normally be lost in linear propagations. Such features can include evanescent waves and peripheral waves, such that an image thus obtained are inherently wide-angle, farfield form of microscopy.

  19. BRST charge for nonlinear algebras

    CERN Document Server

    Buchbinder, I L

    2007-01-01

    We study the construction of the classical nilpotent canonical BRST charge for the nonlinear gauge algebras where a commutator (in terms of Poisson brackets) of the constraints is a finite order polynomial of the constraints.

  20. Nonlinear optics: the next decade.

    Science.gov (United States)

    Kivshar, Yuri S

    2008-12-22

    This paper concludes the Focus Serial assembled of invited papers in key areas of nonlinear optics (Editors: J.M. Dudley and R.W. Boyd), and it discusses new directions for future research in this field.

  1. Nonlinear opto-mechanical pressure

    CERN Document Server

    Conti, Claudio

    2014-01-01

    A transparent material exhibits ultra-fast optical nonlinearity and is subject to optical pressure if irradiated by a laser beam. However, the effect of nonlinearity on optical pressure is often overlooked, even if a nonlinear optical pressure may be potentially employed in many applications, as optical manipulation, biophysics, cavity optomechanics, quantum optics, optical tractors, and is relevant in fundamental problems as the Abraham-Minkoswky dilemma, or the Casimir effect. Here we show that an ultra-fast nonlinear polarization gives indeed a contribution to the optical pressure that also is negative in certain spectral ranges; the theoretical analysis is confirmed by first-principles simulations. An order of magnitude estimate shows that the effect can be observable by measuring the deflection of a membrane made by graphene.

  2. Nonlinear programming analysis and methods

    CERN Document Server

    Avriel, Mordecai

    2012-01-01

    This text provides an excellent bridge between principal theories and concepts and their practical implementation. Topics include convex programming, duality, generalized convexity, analysis of selected nonlinear programs, techniques for numerical solutions, and unconstrained optimization methods.

  3. Nonlinear optics principles and applications

    CERN Document Server

    Li, Chunfei

    2017-01-01

    This book reflects the latest advances in nonlinear optics. Besides the simple, strict mathematical deduction, it also discusses the experimental verification and possible future applications, such as the all-optical switches. It consistently uses the practical unit system throughout. It employs simple physical images, such as "light waves" and "photons" to systematically explain the main principles of nonlinear optical effects. It uses the first-order nonlinear wave equation in frequency domain under the condition of “slowly varying amplitude approximation" and the classical model of the interaction between the light and electric dipole. At the same time, it also uses the rate equations based on the energy-level transition of particle systems excited by photons and the energy and momentum conservation principles to explain the nonlinear optical phenomenon. The book is intended for researchers, engineers and graduate students in the field of the optics, optoelectronics, fiber communication, information tech...

  4. Hilbert complexes of nonlinear elasticity

    Science.gov (United States)

    Angoshtari, Arzhang; Yavari, Arash

    2016-12-01

    We introduce some Hilbert complexes involving second-order tensors on flat compact manifolds with boundary that describe the kinematics and the kinetics of motion in nonlinear elasticity. We then use the general framework of Hilbert complexes to write Hodge-type and Helmholtz-type orthogonal decompositions for second-order tensors. As some applications of these decompositions in nonlinear elasticity, we study the strain compatibility equations of linear and nonlinear elasticity in the presence of Dirichlet boundary conditions and the existence of stress functions on non-contractible bodies. As an application of these Hilbert complexes in computational mechanics, we briefly discuss the derivation of a new class of mixed finite element methods for nonlinear elasticity.

  5. Studies of Nonlinear Problems. I

    Science.gov (United States)

    Fermi, E.; Pasta, J.; Ulam, S.

    1955-05-01

    A one-dimensional dynamical system of 64 particles with forces between neighbors containing nonlinear terms has been studied on the Los Alamos computer MANIAC I. The nonlinear terms considered are quadratic, cubic, and broken linear types. The results are analyzed into Fourier components and plotted as a function of time. The results show very little, if any, tendency toward equipartition of energy among the degrees of freedom.

  6. Nonlinear magnetization dynamics in nanosystems

    CERN Document Server

    Mayergoyz, Isaak D; Serpico, Claudio

    2014-01-01

    As data transfer rates increase within the magnetic recording industry, improvements in device performance and reliability crucially depend on the thorough understanding of nonlinear magnetization dynamics at a sub-nanoscale level. This book offers a modern, stimulating approach to the subject of nonlinear magnetization dynamics by discussing important aspects such as the Landau-Lifshitz-Gilbert (LLG) equation, analytical solutions, and the connection between the general topological and structural aspects of dynamics. An advanced reference for the study and understanding of non

  7. Nonlinear Observers for Gyro Calibration

    Science.gov (United States)

    Thienel, Julie; Sanner, Robert M.

    2003-01-01

    Nonlinear observers for gyro calibration are presented. The first observer estimates a constant gyro bias. The second observer estimates scale factor errors. The third observer estimates the gyro alignment for three orthogonal gyros. The convergence properties of all three observers are discussed. Additionally, all three observers are coupled with a nonlinear control algorithm. The stability of each of the resulting closed loop systems is analyzed. Simulated test results are presented for each system.

  8. Nonlinear dynamics in atom optics

    Energy Technology Data Exchange (ETDEWEB)

    Chen Wenyu; Dyrting, S.; Milburn, G.J. [Queensland Univ., St. Lucia, QLD (Australia). Dept. of Physics

    1996-12-31

    In this paper theoretical work on classical and quantum nonlinear dynamics of cold atoms is reported. The basic concepts in nonlinear dynamics are reviewed and then applied to the motion of atoms in time-dependent standing waves and to the atomic bouncer. The quantum dynamics for the cases of regular and chaotic classical dynamics is described. The effect of spontaneous emission and external noise is also discussed. 104 refs., 1 tab., 21 figs.

  9. A Nonlinear Transfer Operator Theorem

    Science.gov (United States)

    Pollicott, Mark

    2017-02-01

    In recent papers, Kenyon et al. (Ergod Theory Dyn Syst 32:1567-1584 2012), and Fan et al. (C R Math Acad Sci Paris 349:961-964 2011, Adv Math 295:271-333 2016) introduced a form of non-linear thermodynamic formalism based on solutions to a non-linear equation using matrices. In this note we consider the more general setting of Hölder continuous functions.

  10. Nonlinear programming analysis and methods

    CERN Document Server

    Avriel, Mordecai

    2003-01-01

    Comprehensive and complete, this overview provides a single-volume treatment of key algorithms and theories. The author provides clear explanations of all theoretical aspects, with rigorous proof of most results. The two-part treatment begins with the derivation of optimality conditions and discussions of convex programming, duality, generalized convexity, and analysis of selected nonlinear programs. The second part concerns techniques for numerical solutions and unconstrained optimization methods, and it presents commonly used algorithms for constrained nonlinear optimization problems. This g

  11. Nonlinear acoustics in biomedical ultrasound

    Science.gov (United States)

    Cleveland, Robin O.

    2015-10-01

    Ultrasound is widely used to image inside the body; it is also used therapeutically to treat certain medical conditions. In both imaging and therapy applications the amplitudes employed in biomedical ultrasound are often high enough that nonlinear acoustic effects are present in the propagation: the effects have the potential to be advantageous in some scenarios but a hindrance in others. In the case of ultrasound imaging the nonlinearity produces higher harmonics that result in images of greater quality. However, nonlinear effects interfere with the imaging of ultrasound contrast agents (typically micron sized bubbles with a strong nonlinear response of their own) and nonlinear effects also result in complications when derating of pressure measurements in water to in situ values in tissue. High intensity focused ultrasound (HIFU) is emerging as a non-invasive therapeutic modality which can result in thermal ablation of tissue. For thermal ablation, the extra effective attenuation resulting from nonlinear effects can result in enhanced heating of tissue if shock formation occurs in the target region for ablation - a highly desirable effect. However, if nonlinearity is too strong it can also result in undesired near-field heating and reduced ablation in the target region. The disruption of tissue (histotripsy) and fragmentation of kidney stones (lithotripsy) exploits shock waves to produce mechanically based effects, with minimal heating present. In these scenarios it is necessary for the waves to be of sufficient amplitude that a shock exists when the waveform reaches the target region. This talk will discuss how underlying nonlinear phenomenon act in all the diagnostic and therapeutic applications described above.

  12. Nonlinear evolution equations in QCD

    OpenAIRE

    Stasto, A. M.

    2004-01-01

    The following lectures are an introduction to the phenomena of partonic saturation and nonlinear evolution equations in Quantum Chromodynamics. After a short introduction to the linear evolution, the problems of unitarity bound and parton saturation are discussed. The nonlinear Balitsky-Kovchegov evolution equation in the high energy limit is introduced, and the progress towards the understanding of the properties of its solution is reviewed. We discuss the concepts of the saturation scale, g...

  13. Predictive simulation of nonlinear ultrasonics

    Science.gov (United States)

    Shen, Yanfeng; Giurgiutiu, Victor

    2012-04-01

    Most of the nonlinear ultrasonic studies to date have been experimental, but few theoretical predictive studies exist, especially for Lamb wave ultrasonic. Compared with nonlinear bulk waves and Rayleigh waves, nonlinear Lamb waves for structural health monitoring become more challenging due to their multi-mode dispersive features. In this paper, predictive study of nonlinear Lamb waves is done with finite element simulation. A pitch-catch method is used to interrogate a plate with a "breathing crack" which opens and closes under tension and compression. Piezoelectric wafer active sensors (PWAS) used as transmitter and receiver are modeled with coupled field elements. The "breathing crack" is simulated via "element birth and death" technique. The ultrasonic waves generated by the transmitter PWAS propagate into the structure, interact with the "breathing crack", acquire nonlinear features, and are picked up by the receiver PWAS. The features of the wave packets at the receiver PWAS are studied and discussed. The received signal is processed with Fast Fourier Transform to show the higher harmonics nonlinear characteristics. A baseline free damage index is introduced to assess the presence and the severity of the crack. The paper finishes with summary, conclusions, and suggestions for future work.

  14. Nonlinear optical thin films

    Science.gov (United States)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  15. Nonlinear ultrasound wave propagation in thermoviscous fluids

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter

    coupled nonlinear partial differential equations, which resembles those of optical chi-2 materials. We think this result makes a remarkable link between nonlinear acoustics and nonlinear optics. Finally our analysis reveal an exact kink solution to the nonlinear acoustic problem. This kink solution...

  16. New nonlinear optical materials based on ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J P [Department of Physics, Fudan University, Shanghai 200433 (China); Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Yu, K W [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China)

    2006-01-01

    We exploit theoretically a new class of magneto-controlled nonlinear optical material based on ferrofluids in which ferromagnetic nanoparticles are coated with a nonmagnetic metallic nonlinear shell. Such an optical material can have anisotropic nonlinear optical properties and a giant enhancement of nonlinearity, as well as an attractive figure of merit.

  17. Graphene - a rather ordinary nonlinear optical material

    CERN Document Server

    khurgin, Jacob B

    2014-01-01

    An analytical expression for the nonlinear refractive index of graphene has been derived and used to obtain the performance metrics of third order nonlinear devices using graphene as a nonlinear medium. None of the metrics is found to be superior to the existing nonlinear optical materials.

  18. Nonlinear models for autoregressive conditional heteroskedasticity

    DEFF Research Database (Denmark)

    Teräsvirta, Timo

    This paper contains a brief survey of nonlinear models of autore- gressive conditional heteroskedasticity. The models in question are parametric nonlinear extensions of the original model by Engle (1982). After presenting the individual models, linearity testing and parameter estimation...... are discussed. Forecasting volatility with nonlinear models is considered. Finally, parametric nonlinear models based on multi- plicative decomposition of the variance receive attention....

  19. Focus issue introduction: nonlinear optics 2013.

    Science.gov (United States)

    Dadap, Jerry I; Karlsson, Magnus; Panoiu, Nicolae C

    2013-12-16

    Nonlinear Optics has continued to develop over the last few years at an extremely fast pace, with significant advances being reported in nonlinear optical metamaterials, optical signal processing, quantum optics, nonlinear optics at subwavelength scale, and biophotonics. These exciting new developments have generated significant potential for a broad spectrum of technological applications in which nonlinear-optical processes play a central role.

  20. Standing waves for discrete nonlinear Schrodinger equations

    OpenAIRE

    Ming Jia

    2016-01-01

    The discrete nonlinear Schrodinger equation is a nonlinear lattice system that appears in many areas of physics such as nonlinear optics, biomolecular chains and Bose-Einstein condensates. By using critical point theory, we establish some new sufficient conditions on the existence results of standing waves for the discrete nonlinear Schrodinger equations. We give an appropriate example to illustrate the conclusion obtained.

  1. BOOK REVIEW: Nonlinear Magnetohydrodynamics

    Science.gov (United States)

    Shafranov, V.

    1998-08-01

    Nonlinear magnetohydrodynamics by Dieter Biskamp is a thorough introduction to the physics of the most impressive non-linear phenomena that occur in conducting magnetoplasmas. The basic systems, in which non-trivial dynamic processes are observed, accompanied by changes of geometry of the magnetic field and the effects of energy transformation (magnetic energy into kinetic energy or the opposite effect in magnetic dynamos), are the plasma magnetic confinement systems for nuclear fusion and space plasmas, mainly the solar plasma. A significant number of the examples of the dynamic processes considered are taken from laboratory plasmas, for which an experimental check of the theory is possible. Therefore, though the book is intended for researchers and students interested in both laboratory, including nuclear fusion, and astrophysical plasmas, it is most probably closer to the first category of reader. In the Introduction the author notes that unlike the hydrodynamics of non-conducting fluids, where the phenomena caused by rapid fluid motions are the most interesting, for plasmas in a strong magnetic field the quasi-static configurations inside which the local dynamic processes occur are often the most important. Therefore, the reader will also find in this book rather traditional material on the theory of plasma equilibrium and stability in magnetic fields. In addition, it is notable that, as opposed to a linear theory, the non-linear theory, as a rule, cannot give quite definite explanations or predictions of phenomena, and consequently there are in the book many results obtained by consideration of numerical models with the use of supercomputers. The treatment of non-linear dynamics is preceded by Chapters 2 to 4, in which the basics of MHD theory are presented with an emphasis on the role of integral invariants of the magnetic helicity type, a derivation of the reduced MHD equations is given, together with examples of the exact solutions of the equilibrium

  2. Complex motions and chaos in nonlinear systems

    CERN Document Server

    Machado, José; Zhang, Jiazhong

    2016-01-01

    This book brings together 10 chapters on a new stream of research examining complex phenomena in nonlinear systems—including engineering, physics, and social science. Complex Motions and Chaos in Nonlinear Systems provides readers a particular vantage of the nature and nonlinear phenomena in nonlinear dynamics that can develop the corresponding mathematical theory and apply nonlinear design to practical engineering as well as the study of other complex phenomena including those investigated within social science.

  3. Atenção humanizada ao recém-nascido de baixo-peso. Método Canguru e cuidado centrado na família: correspondências e especificidades Humanized care for low birth weight newborns. The Kangaroo care Method and family-centered care: correspondence and specificities

    Directory of Open Access Journals (Sweden)

    Marcia de Abreu e Silva Hennig

    2010-01-01

    Full Text Available Este artigo apresenta a Atenção Humanizada ao Recém-Nascido de Baixo-Peso - Método Canguru - como uma diretriz clínica na assistência neonatal, e busca traçar um paralelo com outro importante componente do cuidado infantil descrito na literatura internacional: o cuidado centrado na família. O artigo propõe que a Atenção Humanizada ao Recém-Nascido de Baixo-Peso - Método Canguru seja vista como uma boa prática e seja considerada também no campo das tecnologias em saúde.The main purpose of this paper is to introduce the Human Attention of Low Birth Weight-Kangaroo Care as clinical guidelines in neonatal intensive care. It will also try to link this clinical guideline and another component of neonatal infant care: the Family-Centered Care. Based on this relationship, this paper proposes that Human Attention of Low Birth Weight-Kangaroo Care should be catalogued as a Potentially Better Practices and also, considered as a Health Care Technology.

  4. O Método Mãe Canguru em hospitais públicos do Estado de São Paulo, Brasil: uma análise do processo de implantação Kangaroo Mother Care in public hospitals in the State of São Paulo, Brazil: an analysis of the implementation process

    Directory of Open Access Journals (Sweden)

    Ana Júlia Colameo

    2006-03-01

    Full Text Available Este estudo foi elaborado para analisar a implantação do Método Mãe Canguru em 28 diferentes hospitais públicos do Estado de São Paulo, Brasil. Os hospitais escola, os amigos da criança, os com banco de leite humano e os com mais de 12 profissionais treinados obtiveram melhores escores de implantação. A resistência dos profissionais de saúde à participação da família tem dado um caráter intra-hospitalar ao método. Mudanças no treinamento, incluir os gestores no programa e prever recursos orçamentários para a adoção, avaliação e controle do Método Mãe Canguru são necessários.This study analyzed the implementation of the Kangaroo Mother method in 28 different São Paulo State public hospitals. Teaching hospitals, Baby-Friendly Hospitals, hospitals with human milk banks, and those with more than 12 trained health professionals showed higher implementation scores. Because of staff resistance to family participation in neonatal care, the Kangaroo Mother method is basically applied in-hospital. Changes in the initial training, including manager awareness-raising and proper financial resource allocation, are necessary for implementation, follow-up, assessment, and feedback.

  5. Compressed Sensing with Nonlinear Observations and Related Nonlinear Optimisation Problems

    CERN Document Server

    Blumensath, Thomas

    2012-01-01

    Non-convex constraints have recently proven a valuable tool in many optimisation problems. In particular sparsity constraints have had a significant impact on sampling theory, where they are used in Compressed Sensing and allow structured signals to be sampled far below the rate traditionally prescribed. Nearly all of the theory developed for Compressed Sensing signal recovery assumes that samples are taken using linear measurements. In this paper we instead address the Compressed Sensing recovery problem in a setting where the observations are non-linear. We show that, under conditions similar to those required in the linear setting, the Iterative Hard Thresholding algorithm can be used to accurately recover sparse or structured signals from few non-linear observations. Similar ideas can also be developed in a more general non-linear optimisation framework. In the second part of this paper we therefore present related result that show how this can be done under sparsity and union of subspaces constraints, wh...

  6. Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1995-04-01

    Full Text Available A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END. Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables. No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC with very convincing results.

  7. Nonlinear graphene plasmonics (Conference Presentation)

    Science.gov (United States)

    Cox, Joel D.; Marini, Andrea; Garcia de Abajo, Javier F.

    2016-09-01

    The combination of graphene's intrinsically-high nonlinear optical response with its ability to support long-lived, electrically tunable plasmons that couple strongly with light has generated great expectations for application of the atomically-thin material to nanophotonic devices. These expectations are mainly reinforced by classical analyses performed using the response derived from extended graphene, neglecting finite-size and nonlocal effects that become important when the carbon layer is structured on the nanometer scale in actual device designs. Based on a quantum-mechanical description of graphene using tight-binding electronic states combined with the random-phase approximation, we show that finite-size effects produce large contributions that increase the nonlinear response associated with plasmons in nanostructured graphene to significantly higher levels than previously thought, particularly in the case of Kerr-type optical nonlinearities. Motivated by this finding, we discuss and compare saturable absorption in extended and nanostructured graphene, with or without plasmonic enhancement, within the context of passive mode-locking for ultrafast lasers. We also explore the possibility of high-harmonic generation in doped graphene nanoribbons and nanoislands, where illumination by an infrared pulse of moderate intensity, tuned to a plasmon resonance, is predicted to generate light at harmonics of order 13 or higher, extending over the visible and UV regimes. Our atomistic description of graphene's nonlinear optical response reveals its complex nature in both extended and nanostructured systems, while further supporting the exceptional potential of this material for nonlinear nanophotonic devices.

  8. Introduction to nonlinear dispersive equations

    CERN Document Server

    Linares, Felipe

    2015-01-01

    This textbook introduces the well-posedness theory for initial-value problems of nonlinear, dispersive partial differential equations, with special focus on two key models, the Korteweg–de Vries equation and the nonlinear Schrödinger equation. A concise and self-contained treatment of background material (the Fourier transform, interpolation theory, Sobolev spaces, and the linear Schrödinger equation) prepares the reader to understand the main topics covered: the initial-value problem for the nonlinear Schrödinger equation and the generalized Korteweg–de Vries equation, properties of their solutions, and a survey of general classes of nonlinear dispersive equations of physical and mathematical significance. Each chapter ends with an expert account of recent developments and open problems, as well as exercises. The final chapter gives a detailed exposition of local well-posedness for the nonlinear Schrödinger equation, taking the reader to the forefront of recent research. The second edition of Introdu...

  9. Nonlinear plasmonics at high temperatures

    CERN Document Server

    Sivan, Yonatan

    2016-01-01

    We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on {\\em experimentally}-measured data for the metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution, and thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modelling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high temperature non...

  10. Nonlinear Multigrid for Reservoir Simulation

    DEFF Research Database (Denmark)

    Christensen, Max la Cour; Eskildsen, Klaus Langgren; Engsig-Karup, Allan Peter

    2016-01-01

    A feasibility study is presented on the effectiveness of applying nonlinear multigrid methods for efficient reservoir simulation of subsurface flow in porous media. A conventional strategy modeled after global linearization by means of Newton’s method is compared with an alternative strategy...... modeled after local linearization, leading to a nonlinear multigrid method in the form of the full-approximation scheme (FAS). It is demonstrated through numerical experiments that, without loss of robustness, the FAS method can outperform the conventional techniques in terms of algorithmic and numerical...... efficiency for a black-oil model. Furthermore, the use of the FAS method enables a significant reduction in memory usage compared with conventional techniques, which suggests new possibilities for improved large-scale reservoir simulation and numerical efficiency. Last, nonlinear multilevel preconditioning...

  11. Nonlinear photoacoustic spectroscopy of hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V., E-mail: LHWANG@WUSTL.EDU [Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130 (United States)

    2015-05-18

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

  12. Nonlinear Waves in Complex Systems

    DEFF Research Database (Denmark)

    2007-01-01

    The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations......, it is the universality and robustness of the main models with respect to perturbations that developped the field. This is true for both continuous and discrete equations. In this volume we keep this broad view and draw new perspectives for nonlinear waves in complex systems. In particular we address energy flow...... in Fourier space and equipartition, the role of inhomogeneities and complex geometry and the importance of coupled systems....

  13. Nonlinear dynamics in biological systems

    CERN Document Server

    Carballido-Landeira, Jorge

    2016-01-01

    This book presents recent research results relating to applications of nonlinear dynamics, focusing specifically on four topics of wide interest: heart dynamics, DNA/RNA, cell mobility, and proteins. The book derives from the First BCAM Workshop on Nonlinear Dynamics in Biological Systems, held in June 2014 at the Basque Center of Applied Mathematics (BCAM). At this international meeting, researchers from different but complementary backgrounds, including molecular dynamics, physical chemistry, bio-informatics and biophysics, presented their most recent results and discussed the future direction of their studies using theoretical, mathematical modeling and experimental approaches. Such was the level of interest stimulated that the decision was taken to produce this publication, with the organizers of the event acting as editors. All of the contributing authors are researchers working on diverse biological problems that can be approached using nonlinear dynamics. The book will appeal especially to applied math...

  14. Nonlinear microrheology of living cells

    CERN Document Server

    Kollmannsberger, Philip; Fabry, Ben

    2009-01-01

    The linear rheology of adherent cells is characterized by a power-law creep or stress relaxation response, and proportionality between stiffness and internal prestress. It is unknown whether these observations hold in the physiologically relevant nonlinear regime. We used magnetic tweezers microrheology to measure the time- and force-dependent nonlinear creep response of adherent cells. Cell deformations in response to a stepwise increasing force applied to cytoskeletally bound magnetic beads were analyzed with a nonlinear superposition approach. The creep response followed a weak power law regardless of force. Stiffness and power law exponent both increased with force, indicating stress stiffening as well as fluidization of the cytoskeleton. Softer cells showed a more pronounced stress stiffening, which is quantitatively explained by their smaller internal prestress. Stiffer and more elastic cells showed a more pronounced force-induced fluidization, consistent with predictions from soft glassy rheology. Thes...

  15. A NONLINEAR FEASIBILITY PROBLEM HEURISTIC

    Directory of Open Access Journals (Sweden)

    Sergio Drumond Ventura

    2015-04-01

    Full Text Available In this work we consider a region S ⊂ given by a finite number of nonlinear smooth convex inequalities and having nonempty interior. We assume a point x 0 is given, which is close in certain norm to the analytic center of S, and that a new nonlinear smooth convex inequality is added to those defining S (perturbed region. It is constructively shown how to obtain a shift of the right-hand side of this inequality such that the point x 0 is still close (in the same norm to the analytic center of this shifted region. Starting from this point and using the theoretical results shown, we develop a heuristic that allows us to obtain the approximate analytic center of the perturbed region. Then, we present a procedure to solve the problem of nonlinear feasibility. The procedure was implemented and we performed some numerical tests for the quadratic (random case.

  16. Nonlinear Deformable-body Dynamics

    CERN Document Server

    Luo, Albert C J

    2010-01-01

    "Nonlinear Deformable-body Dynamics" mainly consists in a mathematical treatise of approximate theories for thin deformable bodies, including cables, beams, rods, webs, membranes, plates, and shells. The intent of the book is to stimulate more research in the area of nonlinear deformable-body dynamics not only because of the unsolved theoretical puzzles it presents but also because of its wide spectrum of applications. For instance, the theories for soft webs and rod-reinforced soft structures can be applied to biomechanics for DNA and living tissues, and the nonlinear theory of deformable bodies, based on the Kirchhoff assumptions, is a special case discussed. This book can serve as a reference work for researchers and a textbook for senior and postgraduate students in physics, mathematics, engineering and biophysics. Dr. Albert C.J. Luo is a Professor of Mechanical Engineering at Southern Illinois University, Edwardsville, IL, USA. Professor Luo is an internationally recognized scientist in the field of non...

  17. Nonlinear Resistivity for Magnetohydrodynamical Models

    CERN Document Server

    Lingam, Manasvi; Pfefferlé, David; Comisso, Luca; Bhattacharjee, Amitava

    2016-01-01

    A nonlinear current-dependent resistivity that accurately accounts for the collisional electron-ion momentum transfer rate is derived. It is shown that the Spitzer resistivity overestimates the resistivity in certain observationally relevant regimes. The nonlinear resistivity computed herein is a strictly decreasing function of the current, in contrast to some notable previous proposals. The relative importance of the new expression with respect to the well-established electron inertia and Hall terms is also examined. The subtle implications of this current-dependent resistivity are discussed in the context of plasma systems and phenomena such as magnetic reconnection.

  18. Time Series with Tailored Nonlinearities

    CERN Document Server

    Raeth, C

    2015-01-01

    It is demonstrated how to generate time series with tailored nonlinearities by inducing well- defined constraints on the Fourier phases. Correlations between the phase information of adjacent phases and (static and dynamic) measures of nonlinearities are established and their origin is explained. By applying a set of simple constraints on the phases of an originally linear and uncor- related Gaussian time series, the observed scaling behavior of the intensity distribution of empirical time series can be reproduced. The power law character of the intensity distributions being typical for e.g. turbulence and financial data can thus be explained in terms of phase correlations.

  19. Topics in nonlinear functional analysis

    CERN Document Server

    Nirenberg, Louis

    2001-01-01

    Since its first appearance as a set of lecture notes published by the Courant Institute in 1974, this book served as an introduction to various subjects in nonlinear functional analysis. The current edition is a reprint of these notes, with added bibliographic references. Topological and analytic methods are developed for treating nonlinear ordinary and partial differential equations. The first two chapters of the book introduce the notion of topological degree and develop its basic properties. These properties are used in later chapters in the discussion of bifurcation theory (the possible br

  20. Finite elements of nonlinear continua

    CERN Document Server

    Oden, J T

    2000-01-01

    Geared toward undergraduate and graduate students, this text extends applications of the finite element method from linear problems in elastic structures to a broad class of practical, nonlinear problems in continuum mechanics. It treats both theory and applications from a general and unifying point of view.The text reviews the thermomechanical principles of continuous media and the properties of the finite element method, and then brings them together to produce discrete physical models of nonlinear continua. The mathematical properties of these models are analyzed, along with the numerical s

  1. Nonlinear Control of Heartbeat Models

    Directory of Open Access Journals (Sweden)

    Witt Thanom

    2011-02-01

    Full Text Available This paper presents a novel application of nonlinear control theory to heartbeat models. Existing heartbeat models are investigated and modified by incorporating the control input as a pacemaker to provide the control channel. A nonlinear feedback linearization technique is applied to force the output of the systems to generate artificial electrocardiogram (ECG signal using discrete data as the reference inputs. The synthetic ECG may serve as a flexible signal source to assess the effectiveness of a diagnostic ECG signal-processing device.

  2. Edge detection by nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Yiu-fai

    1994-07-01

    We demonstrate how the formulation of a nonlinear scale-space filter can be used for edge detection and junction analysis. By casting edge-preserving filtering in terms of maximizing information content subject to an average cost function, the computed cost at each pixel location becomes a local measure of edgeness. This computation depends on a single scale parameter and the given image data. Unlike previous approaches which require careful tuning of the filter kernels for various types of edges, our scheme is general enough to be able to handle different edges, such as lines, step-edges, corners and junctions. Anisotropy in the data is handled automatically by the nonlinear dynamics.

  3. Generation of nonlinear vortex precursors

    CERN Document Server

    Chen, Yue-Yue; Liu, Chengpu

    2016-01-01

    We numerically study the propagation of a few-cycle pulse carrying orbital angular momentum (OAM) through a dense atomic system. Nonlinear precursors consisting of high-order vortex har- monics are generated in the transmitted field due to ultrafast Bloch oscillation. The nonlinear precursors survive to propagation effects and are well separated with the main pulse, which provide a straightforward way of measuring precursors. By the virtue of carrying high-order OAM, the obtained vortex precursors as information carriers have potential applications in optical informa- tion and communication fields where controllable loss, large information-carrying capacity and high speed communication are required.

  4. Stability analysis of nonlinear systems

    CERN Document Server

    Lakshmikantham, Vangipuram; Martynyuk, Anatoly A

    2015-01-01

    The book investigates stability theory in terms of two different measure, exhibiting the advantage of employing families of Lyapunov functions and treats the theory of a variety of inequalities, clearly bringing out the underlying theme. It also demonstrates manifestations of the general Lyapunov method, showing how this technique can be adapted to various apparently diverse nonlinear problems. Furthermore it discusses the application of theoretical results to several different models chosen from real world phenomena, furnishing data that is particularly relevant for practitioners. Stability Analysis of Nonlinear Systems is an invaluable single-sourse reference for industrial and applied mathematicians, statisticians, engineers, researchers in the applied sciences, and graduate students studying differential equations.

  5. Higher dimensional nonlinear massive gravity

    CERN Document Server

    Do, Tuan Q

    2016-01-01

    Inspired by a recent ghost-free nonlinear massive gravity in four-dimensional spacetime, we study its higher dimensional scenarios. As a result, we are able to show the constant-like behavior of massive graviton terms for some well-known metrics such as the Friedmann-Lemaitre-Robertson-Walker, Bianchi type I, and Schwarzschild-Tangherlini-(A)dS metrics in a specific five-dimensional nonlinear massive gravity under an assumption that its fiducial metrics are compatible with physical ones. In addition, some simple cosmological solutions of the five-dimensional massive gravity will be figured out consistently.

  6. Wave equation with concentrated nonlinearities

    OpenAIRE

    Noja, Diego; Posilicano, Andrea

    2004-01-01

    In this paper we address the problem of wave dynamics in presence of concentrated nonlinearities. Given a vector field $V$ on an open subset of $\\CO^n$ and a discrete set $Y\\subset\\RE^3$ with $n$ elements, we define a nonlinear operator $\\Delta_{V,Y}$ on $L^2(\\RE^3)$ which coincides with the free Laplacian when restricted to regular functions vanishing at $Y$, and which reduces to the usual Laplacian with point interactions placed at $Y$ when $V$ is linear and is represented by an Hermitean m...

  7. Field guide to nonlinear optics

    CERN Document Server

    Powers, Peter E

    2013-01-01

    Optomechanics is a field of mechanics that addresses the specific design challenges associated with optical systems. This [i]Field Guide [/i]describes how to mount optical components, as well as how to analyze a given design. It is intended for practicing optical and mechanical engineers whose work requires knowledge in both optics and mechanics. This Field Guide is designed for those looking for a condensed and concise source of key concepts, equations, and techniques for nonlinear optics. Topics covered include technologically important effects, recent developments in nonlinear optics

  8. Stability analysis of nonlinear systems with slope restricted nonlinearities.

    Science.gov (United States)

    Liu, Xian; Du, Jiajia; Gao, Qing

    2014-01-01

    The problem of absolute stability of Lur'e systems with sector and slope restricted nonlinearities is revisited. Novel time-domain and frequency-domain criteria are established by using the Lyapunov method and the well-known Kalman-Yakubovich-Popov (KYP) lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

  9. Stability Analysis of Nonlinear Systems with Slope Restricted Nonlinearities

    Directory of Open Access Journals (Sweden)

    Xian Liu

    2014-01-01

    Full Text Available The problem of absolute stability of Lur’e systems with sector and slope restricted nonlinearities is revisited. Novel time-domain and frequency-domain criteria are established by using the Lyapunov method and the well-known Kalman-Yakubovich-Popov (KYP lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

  10. Nonlinearity and nonclassicality in a nanomechanical resonator

    Energy Technology Data Exchange (ETDEWEB)

    Teklu, Berihu [Clermont Universite, Blaise Pascal University, CNRS, PHOTON-N2, Institut Pascal, Aubiere Cedex (France); Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy); Ferraro, Alessandro; Paternostro, Mauro [Queen' s University, Centre for Theoretical Atomic, Molecular, and Optical Physics, School of Mathematics and Physics, Belfast (United Kingdom); Paris, Matteo G.A. [Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy)

    2015-12-15

    We address quantitatively the relationship between the nonlinearity of a mechanical resonator and the nonclassicality of its ground state. In particular, we analyze the nonclassical properties of the nonlinear Duffing oscillator (being driven or not) as a paradigmatic example of a nonlinear nanomechanical resonator. We first discuss how to quantify the nonlinearity of this system and then show that the nonclassicality of the ground state, as measured by the volume occupied by the negative part of the Wigner function, monotonically increases with the nonlinearity in all the working regimes addressed in our study. Our results show quantitatively that nonlinearity is a resource to create nonclassical states in mechanical systems. (orig.)

  11. Analysis of Wave Nonlinear Dispersion Relation

    Institute of Scientific and Technical Information of China (English)

    LI Rui-jie; TAO Jian-fu

    2005-01-01

    The nonlinear dispersion relations and modified relations proposed by Kirby and Hedges have the limitation of intermediate minimum value. To overcome the shortcoming, a new nonlinear dispersion relation is proposed. Based on the summarization and comparison of existing nonlinear dispersion relations, it can be found that the new nonlinear dispersion relation not only keeps the advantages of other nonlinear dispersion relations, but also significantly reduces the relative errors of the nonlinear dispersion relations for a range of the relative water depth of 1<kh<1.5 and has sufficient accuracy for practical purposes.

  12. Topology optimization of nonlinear optical devices

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    2011-01-01

    This paper considers the design of nonlinear photonic devices. The nonlinearity stems from a nonlinear material model with a permittivity that depends on the local time-averaged intensity of the electric field. A finite element model is developed for time-harmonic wave propagation and an incremen......This paper considers the design of nonlinear photonic devices. The nonlinearity stems from a nonlinear material model with a permittivity that depends on the local time-averaged intensity of the electric field. A finite element model is developed for time-harmonic wave propagation...

  13. Non-linear canonical correlation

    NARCIS (Netherlands)

    van der Burg, Eeke; de Leeuw, Jan

    1983-01-01

    Non-linear canonical correlation analysis is a method for canonical correlation analysis with optimal scaling features. The method fits many kinds of discrete data. The different parameters are solved for in an alternating least squares way and the corresponding program is called CANALS. An

  14. Non-Linear Mixed Logit

    DEFF Research Database (Denmark)

    Andersen, Steffen; Harrison, Glenn W.; Hole, Arne Risa

    2012-01-01

    We develop an extension of the familiar linear mixed logit model to allow for the direct estimation of parametric non-linear functions defined over structural parameters. Classic applications include the estimation of coefficients of utility functions to characterize risk attitudes and discountin...

  15. Impurity solitons with quadratic nonlinearities

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Torres, Juan P-; Torner, Lluis

    1998-01-01

    We fmd families of solitary waves mediated by parametric mixing in quadratic nonlinear media that are localized at point-defect impurities. Solitons localized at attractive impurities are found to be dynamically stable. It is shown that localization at the impurity modifies strongly the soliton p...

  16. Stochastic nonlinear differential equations. I

    NARCIS (Netherlands)

    Heilmann, O.J.; Kampen, N.G. van

    1974-01-01

    A solution method is developed for nonlinear differential equations having the following two properties. Their coefficients are stochastic through their dependence on a Markov process. The magnitude of the fluctuations, multiplied with their auto-correlation time, is a small quantity. Under these co

  17. The Nonlinear Theory of FEL

    CERN Document Server

    Badikyan, Karen

    2016-01-01

    The nonlinear theory of relyativistic strophotron is developed. Classical equations of motion are averaged over fast oscillations. The slow motion phase and saturation parameter are found different from usual undulator oscillation parameters. In the strong field approximation the analytical expression of gain is found on higher harmonics of main resonance frequency.

  18. Observation of Nonlinear Compton Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kotseroglou, T.

    2003-12-19

    This experiment tests Quantum Electrodynamics in the strong field regime. Nonlinear Compton scattering has been observed during the interaction of a 46.6 GeV electron beam with a 10{sup 18} W/cm{sup 2} laser beam. The strength of the field achieved was measured by the parameter {eta} = e{var_epsilon}{sub rms}/{omega}mc = 0.6. Data were collected with infrared and green laser photons and circularly polarized laser light. The timing stabilization achieved between the picosecond laser and electron pulses has {sigma}{sub rms} = 2 ps. A strong signal of electrons that absorbed up to 4 infrared photons (or up to 3 green photons) at the same point in space and time, while emitting a single gamma ray, was observed. The energy spectra of the scattered electrons and the nonlinear dependence of the electron yield on the field strength agreed with the simulation over 3 orders of magnitude. The detector could not resolve the nonlinear Compton scattering from the multiple single Compton scattering which produced rates of scattered electrons of the same order of magnitude. Nevertheless, a simulation has studied this difference and concluded that the scattered electron rates observed could not be accounted for only by multiple ordinary Compton scattering; nonlinear Compton scattering processes are dominant for n {ge} 3.

  19. Nonlinear Optics of Hexaphenyl Nanofibers

    DEFF Research Database (Denmark)

    Balzer, Frank; Al-Shamery, Katharina; Neuendorf, Rolf

    2003-01-01

    measurements reveal that the nonlinear optical transition dipole moment is oriented with an angle of 75° with respect to the needles long axes. The absolute value of the macroscopic second-order susceptibility, averaged over a size distribution of p-6P nanoaggregates, is estimated to be of the order of 6...

  20. Nonlinear intravascular ultrasound contrast imaging

    NARCIS (Netherlands)

    Goertz, David E.; Frijlink, Martijn E.; de Jong, N.; van der Steen, Antonius F.W.

    2006-01-01

    Nonlinear contrast agent imaging with intravascular ultrasound (IVUS) is investigated using a prototype IVUS system and an experimental small bubble contrast agent. The IVUS system employed a mechanically scanned single element transducer and was operated at a 20 MHz transmit frequency (F20) for

  1. Nonlinear wavetrains in viscous conduits

    Science.gov (United States)

    Maiden, Michelle; Hoefer, Mark

    2016-11-01

    Viscous fluid conduits provide an ideal system for the study of dissipationless, dispersive hydrodynamics. A dense, viscous fluid serves as the background medium through which a lighter, less viscous fluid buoyantly rises. If the interior fluid is continuously injected, a deformable pipe forms. The long wave interfacial dynamics are well-described by a dispersive nonlinear partial differential equation. In this talk, experiments, numerics, and asymptotics of the viscous fluid conduit system will be presented. Structures at multiple length scales are discussed, including solitons, dispersive shock waves, and periodic waves. Modulations of periodic waves will be explored in the weakly nonlinear regime with the Nonlinear Schrödinger (NLS) equation. Modulational instability (stability) is identified for sufficiently short (long) periodic waves due to a change in dispersion curvature. These asymptotic results are confirmed by numerical simulations of perturbed nonlinear periodic wave solutions. Also, numerically observed are envelope bright and dark solitons well approximated by NLS. This work was partially supported by NSF CAREER DMS-1255422 (M.A.H.) and NSF GRFP (M.D.M.).

  2. Quantum nonlinear optics without photons

    Science.gov (United States)

    Stassi, Roberto; Macrı, Vincenzo; Kockum, Anton Frisk; Di Stefano, Omar; Miranowicz, Adam; Savasta, Salvatore; Nori, Franco

    2017-08-01

    Spontaneous parametric down-conversion is a well-known process in quantum nonlinear optics in which a photon incident on a nonlinear crystal spontaneously splits into two photons. Here we propose an analogous physical process where one excited atom directly transfers its excitation to a pair of spatially separated atoms with probability approaching 1. The interaction is mediated by the exchange of virtual rather than real photons. This nonlinear atomic process is coherent and reversible, so the pair of excited atoms can transfer the excitation back to the first one: the atomic analog of sum-frequency generation of light. The parameters used to investigate this process correspond to experimentally demonstrated values in ultrastrong circuit quantum electrodynamics. This approach can be extended to realize other nonlinear interatomic processes, such as four-atom mixing, and is an attractive architecture for the realization of quantum devices on a chip. We show that four-qubit mixing can efficiently implement quantum repetition codes and, thus, can be used for error-correction codes.

  3. Cosmological effects of nonlinear electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Novello, M [Instituto de Cosmologia Relatividade Astrofisica (ICRA-Brasil/CBPF), Rua Dr Xavier Sigaud, 150, CEP 22290-180, Rio de Janeiro (Brazil); Goulart, E [Instituto de Cosmologia Relatividade Astrofisica (ICRA-Brasil/CBPF), Rua Dr Xavier Sigaud, 150, CEP 22290-180, Rio de Janeiro (Brazil); Salim, J M [Instituto de Cosmologia Relatividade Astrofisica (ICRA-Brasil/CBPF), Rua Dr Xavier Sigaud, 150, CEP 22290-180, Rio de Janeiro (Brazil); Bergliaffa, S E Perez [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro, R. Sao Francisco Xavier, 524, Maracana, CEP 20559-900, Rio de Janeiro (Brazil)

    2007-06-07

    It will be shown that a given realization of nonlinear electrodynamics, used as a source of Einstein's equations, generates a cosmological model with interesting features, namely a phase of current cosmic acceleration, and the absence of an initial singularity, thus pointing to a way of solving two important problems in cosmology.

  4. On Nonlinear Higher Spin Curvature

    OpenAIRE

    Manvelyan, Ruben(Yerevan Physics Institute, Alikhanian Br. St. 2, Yerevan, 0036, Armenia); Mkrtchyan, Karapet; Rühl, Werner; Tovmasyan, Murad

    2011-01-01

    We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider in detail the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the deWit-Freedman curvature.

  5. On nonlinear higher spin curvature

    Energy Technology Data Exchange (ETDEWEB)

    Manvelyan, Ruben, E-mail: manvel@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Mkrtchyan, Karapet, E-mail: karapet@yerphi.a [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia); Ruehl, Werner, E-mail: ruehl@physik.uni-kl.d [Department of Physics, Erwin Schroedinger Strasse, Technical University of Kaiserslautern, Postfach 3049, 67653 Kaiserslautern (Germany); Tovmasyan, Murad, E-mail: mtovmasyan@ysu.a [Yerevan Physics Institute, Alikhanian Br. Str. 2, 0036 Yerevan (Armenia)

    2011-05-09

    We present the first nonlinear term of the higher spin curvature which is covariant with respect to deformed gauge transformations that are linear in the field. We consider the case of spin 3 after presenting spin 2 as an example, and then construct the general spin s quadratic term of the de Wit-Freedman curvature.

  6. Nonlinear smoothing for random fields

    NARCIS (Netherlands)

    Aihara, Shin Ichi; Bagchi, Arunabha

    1995-01-01

    Stochastic nonlinear elliptic partial differential equations with white noise disturbances are studied in the countably additive measure set up. Introducing the Onsager-Machlup function to the system model, the smoothing problem for maximizing the modified likelihood functional is solved and the exp

  7. Practical stability of nonlinear systems

    CERN Document Server

    Lakshmikantham, Vangipuram; Martynyuk, Anatolii Andreevich

    1990-01-01

    This is the first book that deals with practical stability and its development. It presents a systematic study of the theory of practical stability in terms of two different measures and arbitrary sets and demonstrates the manifestations of general Lyapunov's method by showing how this effective technique can be adapted to investigate various apparently diverse nonlinear problems including control systems and multivalued differential equations.

  8. The virial theorem for nonlinear problems

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal DIaz del Castillo 340, Colima (Mexico); Fernandez, Francisco M [INIFTA (UNLP, CCT La Plata-CONICET), Division Quimica Teorica, Blvd 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)], E-mail: paolo.amore@gmail.com, E-mail: fernande@quimica.unlp.edu.ar

    2009-09-15

    We show that the virial theorem provides a useful simple tool for approximating nonlinear problems. In particular, we consider conservative nonlinear oscillators and obtain the same main result derived earlier from the expansion in Chebyshev polynomials. (letters and comments)

  9. Nonlinear rheological models for structured interfaces

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2010-01-01

    The GENERIC formalism is a formulation of nonequilibrium thermodynamics ideally suited to develop nonlinear constitutive equations for the stress–deformation behavior of complex interfaces. Here we develop a GENERIC model for multiphase systems with interfaces displaying nonlinear viscoelastic stres

  10. International Conference on Applications in Nonlinear Dynamics

    CERN Document Server

    Longhini, Patrick; Palacios, Antonio

    2017-01-01

    This book presents collaborative research works carried out by experimentalists and theorists around the world in the field of nonlinear dynamical systems. It provides a forum for applications of nonlinear systems while solving practical problems in science and engineering. Topics include: Applied Nonlinear Optics, Sensor, Radar & Communication Signal Processing, Nano Devices, Nonlinear Biomedical Applications, Circuits & Systems, Coupled Nonlinear Oscillator, Precision Timing Devices, Networks, and other contemporary topics in the general field of Nonlinear Science. This book provides a comprehensive report of the various research projects presented at the International Conference on Applications in Nonlinear Dynamics (ICAND 2016) held in Denver, Colorado, 2016. It can be a valuable tool for scientists and engineering interested in connecting ideas and methods in nonlinear dynamics with actual design, fabrication and implementation of engineering applications or devices.

  11. Hamiltonian realizations of nonlinear adjoint operators

    NARCIS (Netherlands)

    Fujimoto, Kenji; Scherpen, Jacquelien M.A.; Gray, W. Steven

    2002-01-01

    This paper addresses the issue of state-space realizations for nonlinear adjoint operators. In particular, the relationships between nonlinear Hilbert adjoint operators, Hamiltonian extensions and port-controlled Hamiltonian systems are established. Then, characterizations of the adjoints of control

  12. Hamiltonian Realizations of Nonlinear Adjoint Operators

    NARCIS (Netherlands)

    Fujimoto, Kenji; Scherpen, Jacquelien M.A.; Gray, W. Steven

    2000-01-01

    This paper addresses state-space realizations for nonlinear adjoint operators. In particular the relationship among nonlinear Hilbert adjoint operators, Hamiltonian extensions and port-controlled Hamiltonian systems are clarified. The characterization of controllability, observability and Hankel ope

  13. Nonlinear Least Squares for Inverse Problems

    CERN Document Server

    Chavent, Guy

    2009-01-01

    Presents an introduction into the least squares resolution of nonlinear inverse problems. This title intends to develop a geometrical theory to analyze nonlinear least square (NLS) problems with respect to their quadratic wellposedness, that is, both wellposedness and optimizability

  14. Nonlinear dynamics by mode superposition

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, R.E.

    1976-01-01

    A mode superposition technique for approximately solving nonlinear initial-boundary-value problems of structural dynamics is discussed, and results for examples involving large deformation are compared to those obtained with implicit direct integration methods such as the Newmark generalized acceleration and Houbolt backward-difference operators. The initial natural frequencies and mode shapes are found by inverse power iteration with the trial vectors for successively higher modes being swept by Gram-Schmidt orthonormalization at each iteration. The subsequent modal spectrum for nonlinear states is based upon the tangent stiffness of the structure and is calculated by a subspace iteration procedure that involves matrix multiplication only, using the most recently computed spectrum as an initial estimate. Then, a precise time integration algorithm that has no artificial damping or phase velocity error for linear problems is applied to the uncoupled modal equations of motion. Squared-frequency extrapolation is examined for nonlinear problems as a means by which these qualities of accuracy and precision can be maintained when the state of the system (and, thus, the modal spectrum) is changing rapidly. The results indicate that a number of important advantages accrue to nonlinear mode superposition: (a) there is no significant difference in total solution time between mode superposition and implicit direct integration analyses for problems having narrow matric half-bandwidth (in fact, as bandwidth increases, mode superposition becomes more economical), (b) solution accuracy is under better control since the analyst has ready access to modal participation factors and the ratios of time step size to modal period, and (c) physical understanding of nonlinear dynamic response is improved since the analyst is able to observe the changes in the modal spectrum as deformation proceeds.

  15. Interaction nonlinearity in asphalt binders

    Science.gov (United States)

    Motamed, Arash; Bhasin, Amit; Liechti, Kenneth M.

    2012-05-01

    Asphalt mixtures are complex composites that comprise aggregate, asphalt binder, and air. Several research studies have shown that the mechanical behavior of the asphalt mixture is strongly influenced by the matrix, i.e. the asphalt binder. Characterization and a thorough understanding of the binder behavior is the first and crucial step towards developing an accurate constitutive model for the composite. Accurate constitutive models for the constituent materials are critical to ensure accurate performance predictions at a material and structural level using micromechanics. This paper presents the findings from a systematic investigation into the nature of the linear and nonlinear response of asphalt binders subjected to different types of loading using the Dynamic Shear Rheometer (DSR). Laboratory test data show that a compressive normal force is generated in an axially constrained specimen subjected to torsional shear. This paper investigates the source of this normal force and demonstrates that the asphalt binder can dilate when subjected to shear loads. This paper also presents the findings from a study conducted to investigate the source of the nonlinearity in the asphalt binder. Test results demonstrate that the application of cyclic shear loads results in the development of a normal force and a concomitant reduction in the dynamic shear modulus. This form of nonlinear response is referred to as an "interaction nonlinearity". A combination of experimental and analytical tools is used to demonstrate and verify the presence of this interaction nonlinearity in asphalt binders. The findings from this study highlight the importance of modeling the mechanical behavior of asphalt binders based on the overall stress state of the material.

  16. treated rats

    African Journals Online (AJOL)

    aghomotsegin

    2014-01-08

    Jan 8, 2014 ... Our results show, for the first time, that oral administration of C. edulis ... the exact mechanisms of these hematological changes produced by .... Hematological analysis .... rats are subjected to the additional stress of hypoxia to.

  17. Nonlinear Michelson interferometer for improved quantum metrology

    Science.gov (United States)

    Luis, Alfredo; Rivas, Ángel

    2015-08-01

    We examine quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. This nonlinear interferometer is illuminated by pulses of classical light. This strategy combines the robustness against practical imperfections of classical light with the improvement provided by nonlinear processes. Regarding ultimate quantum limits, we stress that, as a difference with linear schemes, the nonlinearity introduces pulse duration as a new variable into play along with the energy resources.

  18. Detecting the Nonlinearity of Fish Acoustic Signals

    Institute of Scientific and Technical Information of China (English)

    REN Xinmin; YIN Li

    2006-01-01

    This paper discusses the nonlinearity of fish acoustic signals by using the surrogate data method.We compare the difference of three test statistics - time-irreversibility Trey, correlation dimension D2 and auto mutual information function Ⅰbetween the original data and the surrogate data.We come to the conclusion that there exists nonlinearity in the fish acoustic signals and there exist deterministic nonlinear components; therefore nonlinear dynamic theory can be used to analyze fish acoustic signals.

  19. Nonlinear Markov Control Processes and Games

    Science.gov (United States)

    2012-11-15

    further research we indicated possible extensions to state spaces with nontrivial geometry, to the controlled nonlinear quantum dynamic semigroups and...space nonlinear Markov semigroup is a one-parameter semigroup of (possibly nonlinear) transformations of the unit simplex in n-dimensional Euclidean...certain mixing property of nonlinear transition probabilities. In case of the semigroup parametrized by continuous time one defines its generator as the

  20. Nonlinear metrology with a quantum interface

    OpenAIRE

    Napolitano, M.; Mitchell, M. W.

    2009-01-01

    We describe nonlinear quantum atom-light interfaces and nonlinear quantum metrology in the collective continuous variable formalism. We develop a nonlinear effective Hamiltonian in terms of spin and polarization collective variables and show that model Hamiltonians of interest for nonlinear quantum metrology can be produced in $^{87}$Rb ensembles. With these Hamiltonians, metrologically relevant atomic properties, e.g. the collective spin, can be measured better than the "Heisenberg limit" $\\...

  1. Nonlinear Michelson interferometer for improved quantum metrology

    OpenAIRE

    Luis Aina, Alfredo; Rivas Vargas, Ángel

    2015-01-01

    We examine quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. This nonlinear interferometer is illuminated by pulses of classical light. This strategy combines the robustness against practical imperfections of classical light with the improvement provided by nonlinear processes. Regarding ultimate quantum limits, we stress that, as a difference with linear schemes, the nonlinearity introduces pulse duration as a new variable into play along with the ene...

  2. Standing waves for discrete nonlinear Schrodinger equations

    Directory of Open Access Journals (Sweden)

    Ming Jia

    2016-07-01

    Full Text Available The discrete nonlinear Schrodinger equation is a nonlinear lattice system that appears in many areas of physics such as nonlinear optics, biomolecular chains and Bose-Einstein condensates. By using critical point theory, we establish some new sufficient conditions on the existence results of standing waves for the discrete nonlinear Schrodinger equations. We give an appropriate example to illustrate the conclusion obtained.

  3. Nonlinear Young integrals via fractional calculus

    OpenAIRE

    Hu, Yaozhong (1961-); Le, Khoa

    2015-01-01

    For H\\"older continuous functions $W(t,x)$ and $\\varphi_t$, we define nonlinear integral $\\int_a^b W(dt, \\varphi_t)$ via fractional calculus. This nonlinear integral arises naturally in the Feynman-Kac formula for stochastic heat equations with random coefficients. We also define iterated nonlinear integrals.

  4. Nonlinear approaches in engineering applications 2

    CERN Document Server

    Jazar, Reza N

    2013-01-01

    Provides updated principles and applications of the nonlinear approaches in solving engineering and physics problems Demonstrates how nonlinear approaches may open avenues to better, safer, cheaper systems with less energy consumption Has a strong emphasis on the application, physical meaning, and methodologies of nonlinear approaches in different engineering and science problems

  5. Nonlinear quasimodes near elliptic periodic geodesics

    CERN Document Server

    Albin, Pierre; Marzuola, Jeremy L; Thomann, Laurent

    2011-01-01

    We consider the nonlinear Schr\\"odinger equation on a compact manifold near an elliptic periodic geodesic. Using a geometric optics construction, we construct quasimodes to a nonlinear stationary problem which are highly localized near the periodic geodesic. We show the nonlinear Schr\\"odinger evolution of such a quasimode remains localized near the geodesic, at least for short times.

  6. Nonlinear time series modelling: an introduction

    OpenAIRE

    Simon M. Potter

    1999-01-01

    Recent developments in nonlinear time series modelling are reviewed. Three main types of nonlinear models are discussed: Markov Switching, Threshold Autoregression and Smooth Transition Autoregression. Classical and Bayesian estimation techniques are described for each model. Parametric tests for nonlinearity are reviewed with examples from the three types of models. Finally, forecasting and impulse response analysis is developed.

  7. Variational principles for nonlinear piezoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Ramos, R.; Guinovart-Diaz, R. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Pobedria, B.E. [Moscow State University M. V. Lomonosov, Composites Department, Moscow (Russian Federation); Padilla, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas (IIMAS), Cd. Universitaria, Mexico D.F. (Mexico); Bravo-Castillero, J. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Campus Estado de Mexico. Division de Arquitectura e Ingenieria, Instituto Tecnologico de Estudios Superiores de Monterrey, Atizapan de Zaragoza, Estado de Mexico (Mexico); Maugin, G.A. [Universite Pierre et Marie Curie. Case 162, UMR 7607 CNRS, Laboratoire de Modelisation en Mecanique, Paris Cedex 05 (France)

    2004-12-01

    In the present paper, we consider the behavior of nonlinear piezoelectric materials by generalization for this case of the Hashin-Shtrikman variational principles. The new general formulation used here differs from others, because, it gives the possibility to evaluate the upper and lower Hashin-Shtrikman bounds for specific physical nonlinearities of piezoelectric materials. Geometrical nonlinearities are not considered. (orig.)

  8. Unsymmetrical squaraines for nonlinear optical materials

    Science.gov (United States)

    Marder, Seth R. (Inventor); Chen, Chin-Ti (Inventor); Cheng, Lap-Tak (Inventor)

    1996-01-01

    Compositions for use in non-linear optical devices. The compositions have first molecular electronic hyperpolarizability (.beta.) either positive or negative in sign and therefore display second order non-linear optical properties when incorporated into non-linear optical devices.

  9. Nonlinear parametric instability of wind turbine wings

    DEFF Research Database (Denmark)

    Larsen, Jesper Winther; Nielsen, Søren R.K.

    2006-01-01

    Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability...

  10. On balanced truncation for symmetric nonlinear systems

    NARCIS (Netherlands)

    Fujimoto, K.; Scherpen, Jacqueline M.A.

    2014-01-01

    This paper is concerned with model order reduction based on balanced realization for symmetric nonlinear systems. A new notion of symmetry for nonlinear systems was characterized recently. It plays an important role in linear systems theory and is expected to provide new insights to nonlinear system

  11. Introducing Nonlinear Pricing into Consumer Choice Theory.

    Science.gov (United States)

    DeSalvo, Joseph S.; Huq, Mobinul

    2002-01-01

    Describes and contrasts nonlinear and linear pricing in consumer choice theory. Discusses the types of nonlinear pricing: block-declining tariff, two-part tariff, three-part tariff, and quality discounts or premia. States that understanding nonlinear pricing enhances student comprehension of consumer choice theory. Suggests teaching the concept in…

  12. Nonlinear parametric instability of wind turbine wings

    DEFF Research Database (Denmark)

    Larsen, Jesper Winther; Nielsen, Søren R.K.

    2006-01-01

    Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability o...

  13. Solitons in quadratic nonlinear photonic crystals

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2001-01-01

    We study solitons in one-dimensional quadratic nonlinear photonic crystals with modulation of both the linear and nonlinear susceptibilities. We derive averaged equations that include induced cubic nonlinearities, which can be defocusing, and we numerically find previously unknown soliton families...

  14. Common large innovations across nonlinear time series

    NARCIS (Netherlands)

    Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)

    2002-01-01

    textabstractWe propose a multivariate nonlinear econometric time series model, which can be used to examine if there is common nonlinearity across economic variables. The model is a multivariate censored latent effects autoregression. The key feature of this model is that nonlinearity appears as sep

  15. Nonlinear observer design for a nonlinear string/cable FEM model using contraction theory

    DEFF Research Database (Denmark)

    Turkyilmaz, Yilmaz; Jouffroy, Jerome; Egeland, Olav

    Contraction theory is a recently developed nonlinear analysis tool which may be useful for solving a variety of nonlinear control problems. In this paper, using Contraction theory, a nonlinear observer is designed for a general nonlinear cable/string FEM (Finite Element Method) model. The cable...

  16. Nonlinear observer design for a nonlinear string/cable FEM model using contraction theory

    DEFF Research Database (Denmark)

    Turkyilmaz, Yilmaz; Jouffroy, Jerome; Egeland, Olav

    Contraction theory is a recently developed nonlinear analysis tool which may be useful for solving a variety of nonlinear control problems. In this paper, using Contraction theory, a nonlinear observer is designed for a general nonlinear cable/string FEM (Finite Element Method) model. The cable...

  17. Processing Approach of Non-linear Adjustment Models in the Space of Non-linear Models

    Institute of Scientific and Technical Information of China (English)

    LI Chaokui; ZHU Qing; SONG Chengfang

    2003-01-01

    This paper investigates the mathematic features of non-linear models and discusses the processing way of non-linear factors which contributes to the non-linearity of a nonlinear model. On the basis of the error definition, this paper puts forward a new adjustment criterion, SGPE.Last, this paper investigates the solution of a non-linear regression model in the non-linear model space and makes the comparison between the estimated values in non-linear model space and those in linear model space.

  18. Enhancement in nonlinear transport in percolating superconductor nonlinear resistor networks. A universality phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G.M. [China Center of Advanced Science and Technology (CCAST), Beijing, BJ (China)]|[Suzhou Univ. (China). Dept. of Physics

    1996-04-01

    In this note we consider the geometrical effects of a percolating system on the nonlinear transport properties in a superconductor-normal conductor nonlinear resistor network. For realistic composites, the nonlinearity may play an important role in the electrical transport phenomena. A typical example consists of studying a nonlinear composite medium in which an inclusion with nonlinear current-field (J-E) characteristics is randomly embedded in a host with either linear or nonlinear J-E response. For such a system, substantial progress in studies of the effective nonlinear response has been made in the past few years. 24 refs.

  19. Nonlinear acoustic propagation in rectangular ducts

    Science.gov (United States)

    Nayfeh, A. H.; Tsai, M.-S.

    1974-01-01

    The method of multiple scales is used to obtain a second-order uniformly valid expansion for nonlinear acoustic wave propagation in a rectangular duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear materials attenuate sound more than linear materials except at high acoustic frequencies. The nonlinear materials produce higher and combination tones which have higher attenuation rates than the fundamentals. Moreover, the attenuation rates of the fundamentals increase with increasing amplitude.

  20. The Effective AC Response of Nonlinear Composites

    Institute of Scientific and Technical Information of China (English)

    WEI En-Bo; GU Guo-Qing

    2001-01-01

    A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form J = σ E + χ|E|2 E with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media vith a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility χ*3ω at the third harmonic frequency.

  1. Nonlinear fiber optics formerly quantum electronics

    CERN Document Server

    Agrawal, Govind

    1995-01-01

    The field of nonlinear fiber optics has grown substantially since the First Edition of Nonlinear Fiber Optics, published in 1989. Like the First Edition, this Second Edition is a comprehensive, tutorial, and up-to-date account of nonlinear optical phenomena in fiber optics. It synthesizes widely scattered research material and presents it in an accessible manner for students and researchers already engaged in or wishing to enter the field of nonlinear fiber optics. Particular attention is paid to the importance of nonlinear effects in the design of optical fiber communication systems. This is

  2. Nonlinear phononics using atomically thin membranes

    Science.gov (United States)

    Midtvedt, Daniel; Isacsson, Andreas; Croy, Alexander

    2014-09-01

    Phononic crystals and acoustic metamaterials are used to tailor phonon and sound propagation properties by utilizing artificial, periodic structures. Analogous to photonic crystals, phononic band gaps can be created, which influence wave propagation and, more generally, allow engineering of the acoustic properties of a system. Beyond that, nonlinear phenomena in periodic structures have been extensively studied in photonic crystals and atomic Bose-Einstein condensates in optical lattices. However, creating nonlinear phononic crystals or nonlinear acoustic metamaterials remains challenging and only few examples have been demonstrated. Here, we show that atomically thin and periodically pinned membranes support coupled localized modes with nonlinear dynamics. The proposed system provides a platform for investigating nonlinear phononics.

  3. Advances in nonlinear optical materials and devices

    Science.gov (United States)

    Byer, Robert L.

    1991-01-01

    The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

  4. The nonlinear piezoelectric tuned vibration absorber

    Science.gov (United States)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  5. CHAOTIC BELT PHENOMENA IN NONLINEAR ELASTIC BEAM

    Institute of Scientific and Technical Information of China (English)

    张年梅; 杨桂通

    2003-01-01

    The chaotic motions of axial compressed nonlinear elastic beam subjected totransverse load were studied. The damping force in the system is nonlinear. Consideringmaterial and geometric nonlinearity, nonlinear governing equation of the system wasderived. By use of nonlinear Galerkin method, differential dynamic system was set up.Melnikov method was used to analyze the characters of the system. The results showed thatchaos may occur in the system when the load parameters P0 and f satisfy some conditions.The zone of chaotic motion was belted. The route from subharmonic bifurcation to chaoswas analyzed. The critical conditions that chaos occurs were determined.

  6. Spin squeezing in nonlinear spin coherent states

    OpenAIRE

    Wang, Xiaoguang

    2001-01-01

    We introduce the nonlinear spin coherent state via its ladder operator formalism and propose a type of nonlinear spin coherent state by the nonlinear time evolution of spin coherent states. By a new version of spectroscopic squeezing criteria we study the spin squeezing in both the spin coherent state and nonlinear spin coherent state. The results show that the spin coherent state is not squeezed in the x, y, and z directions, and the nonlinear spin coherent state may be squeezed in the x and...

  7. Generalized solutions of nonlinear partial differential equations

    CERN Document Server

    Rosinger, EE

    1987-01-01

    During the last few years, several fairly systematic nonlinear theories of generalized solutions of rather arbitrary nonlinear partial differential equations have emerged. The aim of this volume is to offer the reader a sufficiently detailed introduction to two of these recent nonlinear theories which have so far contributed most to the study of generalized solutions of nonlinear partial differential equations, bringing the reader to the level of ongoing research.The essence of the two nonlinear theories presented in this volume is the observation that much of the mathematics concernin

  8. Non-linear Ultrasound Imaging

    DEFF Research Database (Denmark)

    Du, Yigang

    without iteration steps. The ASA is implemented in combination with Field II and extended to simulate the pulsed ultrasound fields. The simulated results from a linear array transducer are made by the ASA based on Field II, and by a released non-linear simulation program- Abersim, respectively....... The calculation speed of the ASA is increased approximately by a factor of 140. For the second harmonic point spread function the error of the full width is 1.5% at -6 dB and 6.4% at -12 dB compared to Abersim. To further investigate the linear and non-linear ultrasound fields, hydrophone measurements.......3% relative to the measurement from a 1 inch diameter transducer. A preliminary study for harmonic imaging using synthetic aperture sequential beamforming (SASB) has been demonstrated. A wire phantom underwater measurement is made by an experimental synthetic aperture real-time ultrasound scanner (SARUS...

  9. Single-cycle nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Max-Planck-Institut fur Quantenoptik; Goulielmakis, E.; Schultze, M.; Hofstetter, M.; Yakovlev, V. S.; Gagnon, J.; Uiberacker, M.; Aquila, A. L.; gullikson, E. M.; attwood, D. T.; Kienberger, R.; Krausz, F.; Kleineberg, U.

    2008-11-05

    Nonlinear optics plays a central role in the advancement of optical science and laser-based technologies. We report on the confinement of the nonlinear interaction of light with matter to a single wave cycle and demonstrate its utility for time-resolved and strong-field science. The electric field of 3.3-femtosecond, 0.72-micron laser pulses with a controlled and measured waveform ionizes atoms near the crests of the central wave cycle, with ionization being virtually switched off outside this interval. Isolated sub-100-attosecond pulses of extreme ultraviolet light (photon energy {approx} 80 electron volts), containing {approx} 0.5 nanojoule of energy, emerge from the interaction with a conversion efficiency of {approx} 10{sup -6}. These tools enable the study of the precision control of electron motion with light fields and electron-electron interactions with a resolution approaching the atomic unit of time ({approx} 24 attoseconds).

  10. New approaches to nonlinear waves

    CERN Document Server

    2016-01-01

    The book details a few of the novel methods developed in the last few years for studying various aspects of nonlinear wave systems. The introductory chapter provides a general overview, thematically linking the objects described in the book. Two chapters are devoted to wave systems possessing resonances with linear frequencies (Chapter 2) and with nonlinear frequencies (Chapter 3). In the next two chapters modulation instability in the KdV-type of equations is studied using rigorous mathematical methods (Chapter 4) and its possible connection to freak waves is investigated (Chapter 5). The book goes on to demonstrate how the choice of the Hamiltonian (Chapter 6) or the Lagrangian (Chapter 7) framework allows us to gain a deeper insight into the properties of a specific wave system. The final chapter discusses problems encountered when attempting to verify the theoretical predictions using numerical or laboratory experiments. All the chapters are illustrated by ample constructive examples demonstrating the app...

  11. Nonlinear ion trap stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mihalcea, Bogdan M; Visan, Gina G, E-mail: bmihal@infim.r [Institute for Laser, Plasma and Radiation Physics (INFLPR), Atomistilor Str. Nr. 409, 077125 Magurele-Bucharest, Jud. Ilfov (Romania)

    2010-09-01

    This paper investigates the dynamics of an ion confined in a nonlinear Paul trap. The equation of motion for the ion is shown to be consistent with the equation describing a damped, forced Duffing oscillator. All perturbing factors are taken into consideration in the approach. Moreover, the ion is considered to undergo interaction with an external electromagnetic field. The method is based on numerical integration of the equation of motion, as the system under investigation is highly nonlinear. Phase portraits and Poincare sections show that chaos is present in the associated dynamics. The system of interest exhibits fractal properties and strange attractors. The bifurcation diagrams emphasize qualitative changes of the dynamics and the onset of chaos.

  12. Understanding nonlinear effects and losses

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, J.

    1995-10-01

    With the planned construction of a large hadron collider (LHC) and a major upgrade of LEP (LEP-II) at CERN, a {Phi}-factory at Frascatti, and B-factories at SLAC (PEP-II) and KEK (KEK-B), we are now entering new energy and intensity regimes in both electron and proton circular colliders. Understanding and accurately estimating dynamic apertures and particle loss rates under both injection and colliding beam conditions is of primary importance. This paper summarizes discussions on Understanding Nonlinear Effects and Losses that took place in Working Group Three at the September 1994 Conference on Nonlinear Dynamics in Particle Accelerators at Arcidosso, Italy. Questions addressed were: {open_quotes}What do simulations indicate as the underlying causes of particle loss?{close_quotes} and {open_quotes}Do experiments agree with simulations-and if not, why not?{close_quotes} Special attention was given to a discrepancy between dynamic aperture measurements and theoretical predictions at HERA.

  13. Nonlinear effects in asymmetric catalysis.

    Science.gov (United States)

    Satyanarayana, Tummanapalli; Abraham, Susan; Kagan, Henri B

    2009-01-01

    There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

  14. Some nonlinear space decomposition algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Xue-Cheng; Espedal, M. [Univ. of Bergen (Norway)

    1996-12-31

    Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.

  15. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  16. LINEAR AND NONLINEAR SEMIDEFINITE PROGRAMMING

    Directory of Open Access Journals (Sweden)

    Walter Gómez Bofill

    2014-12-01

    Full Text Available This paper provides a short introduction to optimization problems with semidefinite constraints. Basic duality and optimality conditions are presented. For linear semidefinite programming some advances by dealing with degeneracy and the semidefinite facial reduction are discussed. Two relatively recent areas of application are presented. Finally a short overview of relevant literature on algorithmic approaches for efficiently solving linear and nonlinear semidefinite programming is provided.

  17. CMOS Nonlinear Signal Processing Circuits

    OpenAIRE

    2010-01-01

    The chapter describes various nonlinear signal processing CMOS circuits, including a high reliable WTA/LTA, simple MED cell, and low-voltage arbitrary order extractor. We focus the discussion on CMOS analog circuit design with reliable, programmable capability, and low voltage operation. It is a practical problem when the multiple identical cells are required to match and realized within a single chip using a conventional process. Thus, the design of high-reliable circuit is indeed needed. Th...

  18. Lagrangian description of nonlinear chromatography

    Institute of Scientific and Technical Information of China (English)

    LIANG Heng; LIU Xiaolong

    2004-01-01

    Under the framework of non-equilibrium thermodynamic separation theory (NTST), Local Lagrangian approach (LLA) was proposed to deal with the essential issues of the convection and diffusion (shock waves) phenomena in nonlinear chromatography with recursion equations based on the three basic theorems, Lagrangian description, continuity axiom and local equilibrium assumption (LEA). This approach remarkably distinguished from the system of contemporary chromatographic theories (Eulerian description-partial differential equations), and can felicitously match modern cybernetics.

  19. Dynamical Imaging using Spatial Nonlinearity

    Science.gov (United States)

    2014-01-29

    Imin )/ (Imax + Imin ) = 0.15 for detection of the bars (from maxima to central dip). For our experimental measurements, the best linear visibility is...Statistical theory for incoherent light propagation in nonlinear media, Physical Review E, 65 (2002) 035602. [52] M.J. Bastiaans, Application of the...1238. [53] M.E. Testorf, B.M. Hennelly, J. Ojeda-Castañeda, Phase-space optics : fundamentals and applications , McGraw-Hill, New York, 2010. [54] K.H

  20. Nonlinear input-output systems

    Science.gov (United States)

    Hunt, L. R.; Luksic, Mladen; Su, Renjeng

    1987-01-01

    Necessary and sufficient conditions that the nonlinear system dot-x = f(x) + ug(x) and y = h(x) be locally feedback equivalent to the controllable linear system dot-xi = A xi + bv and y = C xi having linear output are found. Only the single input and single output case is considered, however, the results generalize to multi-input and multi-output systems.

  1. Robust nonlinear regression in applications

    OpenAIRE

    Lim, Changwon; Sen, Pranab K.; Peddada, Shyamal D.

    2013-01-01

    Robust statistical methods, such as M-estimators, are needed for nonlinear regression models because of the presence of outliers/influential observations and heteroscedasticity. Outliers and influential observations are commonly observed in many applications, especially in toxicology and agricultural experiments. For example, dose response studies, which are routinely conducted in toxicology and agriculture, sometimes result in potential outliers, especially in the high dose gr...

  2. Nonlinear Acoustic Characterization of Targets

    Science.gov (United States)

    2008-01-01

    matching so as to transmit as much energy as possible into the test object. In addition to this limitation, ultrasound is only able to measure range by...metric arrays for standoff analysis of targets. In 1982, Yoneyama[4] discussed the nonlinear interaction of ultrasound with air as the “scattering of... cavitation effect. This produces a rectification at higher frequencies just as a diode does in an electrical circuit. This natural rectification allows

  3. Transformation design and nonlinear Hamiltonians

    CERN Document Server

    Brougham, Thomas; Jex, Igor

    2009-01-01

    We study a class of nonlinear Hamiltonians, with applications in quantum optics. The interaction terms of these Hamiltonians are generated by taking a linear combination of powers of a simple `beam splitter' Hamiltonian. The entanglement properties of the eigenstates are studied. Finally, we show how to use this class of Hamiltonians to perform special tasks such as conditional state swapping, which can be used to generate optical cat states and to sort photons.

  4. Modal Identification Using OMA Techniques: Nonlinearity Effect

    Directory of Open Access Journals (Sweden)

    E. Zhang

    2015-01-01

    Full Text Available This paper is focused on an assessment of the state of the art of operational modal analysis (OMA methodologies in estimating modal parameters from output responses of nonlinear structures. By means of the Volterra series, the nonlinear structure excited by random excitation is modeled as best linear approximation plus a term representing nonlinear distortions. As the nonlinear distortions are of stochastic nature and thus indistinguishable from the measurement noise, a protocol based on the use of the random phase multisine is proposed to reveal the accuracy and robustness of the linear OMA technique in the presence of the system nonlinearity. Several frequency- and time-domain based OMA techniques are examined for the modal identification of simulated and real nonlinear mechanical systems. Theoretical analyses are also provided to understand how the system nonlinearity degrades the performance of the OMA algorithms.

  5. An Adaptive Nonlinear Filter for System Identification

    Directory of Open Access Journals (Sweden)

    Tokunbo Ogunfunmi

    2009-01-01

    Full Text Available The primary difficulty in the identification of Hammerstein nonlinear systems (a static memoryless nonlinear system in series with a dynamic linear system is that the output of the nonlinear system (input to the linear system is unknown. By employing the theory of affine projection, we propose a gradient-based adaptive Hammerstein algorithm with variable step-size which estimates the Hammerstein nonlinear system parameters. The adaptive Hammerstein nonlinear system parameter estimation algorithm proposed is accomplished without linearizing the systems nonlinearity. To reduce the effects of eigenvalue spread as a result of the Hammerstein system nonlinearity, a new criterion that provides a measure of how close the Hammerstein filter is to optimum performance was used to update the step-size. Experimental results are presented to validate our proposed variable step-size adaptive Hammerstein algorithm given a real life system and a hypothetical case.

  6. Adaptive regression for modeling nonlinear relationships

    CERN Document Server

    Knafl, George J

    2016-01-01

    This book presents methods for investigating whether relationships are linear or nonlinear and for adaptively fitting appropriate models when they are nonlinear. Data analysts will learn how to incorporate nonlinearity in one or more predictor variables into regression models for different types of outcome variables. Such nonlinear dependence is often not considered in applied research, yet nonlinear relationships are common and so need to be addressed. A standard linear analysis can produce misleading conclusions, while a nonlinear analysis can provide novel insights into data, not otherwise possible. A variety of examples of the benefits of modeling nonlinear relationships are presented throughout the book. Methods are covered using what are called fractional polynomials based on real-valued power transformations of primary predictor variables combined with model selection based on likelihood cross-validation. The book covers how to formulate and conduct such adaptive fractional polynomial modeling in the s...

  7. Nonlinear filtering for LIDAR signal processing

    Directory of Open Access Journals (Sweden)

    D. G. Lainiotis

    1996-01-01

    Full Text Available LIDAR (Laser Integrated Radar is an engineering problem of great practical importance in environmental monitoring sciences. Signal processing for LIDAR applications involves highly nonlinear models and consequently nonlinear filtering. Optimal nonlinear filters, however, are practically unrealizable. In this paper, the Lainiotis's multi-model partitioning methodology and the related approximate but effective nonlinear filtering algorithms are reviewed and applied to LIDAR signal processing. Extensive simulation and performance evaluation of the multi-model partitioning approach and its application to LIDAR signal processing shows that the nonlinear partitioning methods are very effective and significantly superior to the nonlinear extended Kalman filter (EKF, which has been the standard nonlinear filter in past engineering applications.

  8. Nonlinear and Stochastic Morphological Segregation

    CERN Document Server

    Blanton, M R

    1999-01-01

    I perform a joint counts-in-cells analysis of galaxies of different spectral types using the Las Campanas Redshift Survey (LCRS). Using a maximum-likelihood technique to fit for the relationship between the density fields of early- and late-type galaxies, I find a relative linear bias of $b=0.76\\pm 0.02$. This technique can probe the nonlinearity and stochasticity of the relationship as well. However, the degree to which nonlinear and stochastic fits improve upon the linear fit turns out to depend on the redshift range in question. In particular, there seems to be a systematic difference between the high- and low-redshift halves of the data (respectively, further than and closer than $cz\\approx 36,000$ km/s); all of the signal of stochasticity and nonlinearity comes from the low-redshift portion. Analysis of mock catalogs shows that the peculiar geometry and variable flux limits of the LCRS do not cause this effect. I speculate that the central surface brightness selection criteria of the LCRS may be responsi...

  9. Focus issue introduction: nonlinear photonics.

    Science.gov (United States)

    Akhmediev, Nail; Rottwitt, Karsten

    2012-11-19

    It is now 23 years since the first Topical Meeting "Nonlinear Guided Wave Phenomena" (Houston, TX, February 2-4, 1989) has been organised by George Stegeman and Allan Boardman with support of the Optical Society of America. These series of the OSA conferences known as NLGW, continued under the name "Nonlinear Photonics" starting from 2007. The latest one, in Colorado Springs in June 17-21, 2012 has been a great success despite the fierce fires advancing around the city at the time of the conference. This Focus issue is a collection of several papers presented at the conference with extended content submitted to Optics Express. Although this collection is small in comparison to the total number of papers presented at the conference, it gives a flavor of the topics considered at the meeting. It is also worthy to mention here that the next meeting "Nonlinear Photonics" is planned to be held in Barcelona - one of the main European centers on this subject.

  10. Percepção dos pais sobre a vivência no método mãe-canguru La percepción de los padres en la vivencia del método madre-canguro Perception of parents in experiencing the kangaroo mother method

    Directory of Open Access Journals (Sweden)

    Cláudia Elisângela Fernandes Bis Furlan

    2003-08-01

    institucional del equipo de salud como de la relación con la clientela, posibilitando la comprensión de las dificultades y significados atribuidos a la vivencia y a la optimización del cuidado de enfermería.This study aimed at analyzing the perception of pre-term babies' parents in experiencing the Kangaroo Mother Method. It is a descriptive study with a qualitative approach. Data were collected from semi-structured interviews with 10 parents, held in the first 60 days after the discharge of the pre-term baby from the Kangaroo method, in a philanthropic hospital in the interior of São Paulo State. The parents' perception concerning the experience was grouped in four thematic units: making maternal stay in the Kangaroo Method flexible; favoring the mother-child and family relationship; completing the pre-term newborn's growth and development and developing skills in caring for the child. The obtained data provided information for the organization of care in the Kangaroo Mother Method, from the institutional perspective of the health care team as well as the relationship with clients, which enabled understanding about the difficulties and meanings attributed to the experience and optimization of nursing care.

  11. Waves and Structures in Nonlinear Nondispersive Media General Theory and Applications to Nonlinear Acoustics

    CERN Document Server

    Gurbatov, S N; Saichev, A I

    2012-01-01

    "Waves and Structures in Nonlinear Nondispersive Media: General Theory and Applications to Nonlinear Acoustics” is devoted completely to nonlinear structures. The general theory is given here in parallel with mathematical models. Many concrete examples illustrate the general analysis of Part I. Part II is devoted to applications to nonlinear acoustics, including specific nonlinear models and exact solutions, physical mechanisms of nonlinearity, sawtooth-shaped wave propagation, self-action phenomena, nonlinear resonances and engineering application (medicine, nondestructive testing, geophysics, etc.). This book is designed for graduate and postgraduate students studying the theory of nonlinear waves of various physical nature. It may also be useful as a handbook for engineers and researchers who encounter the necessity of taking nonlinear wave effects into account of their work. Dr. Gurbatov S.N. is the head of Department, and Vice Rector for Research of Nizhny Novgorod State University. Dr. Rudenko O.V. is...

  12. SPHERICAL NONLINEAR PULSES FOR THE SOLUTIONS OF NONLINEAR WAVE EQUATIONS Ⅱ, NONLINEAR CAUSTIC

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This article discusses spherical pulse like solutions of the system of semilinear wave equations with the pulses focusing at a point and emerging outgoing in three space variables. In small initial data case, it shows that the nonlinearities have a strong effect at the focal point. Scattering operator is introduced to describe the caustic crossing. With the aid of the L∞ norms, it analyzes the relative errors in approximate solutions.

  13. Probing hysteretic elasticity in weakly nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  14. Nonlinear susceptibility magnitude imaging of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ficko, Bradley W., E-mail: Bradley.W.Ficko@Dartmouth.edu; Giacometti, Paolo; Diamond, Solomon G.

    2015-03-15

    This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R{sup 2}=0.99, CNR=84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R{sup 2}>0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI. - Highlights: • Development of a nonlinear susceptibility magnitude imaging model • Demonstration of nonlinear SMI with primary and harmonic frequencies • Demonstration of nonlinear SMI with primary and intermodulation

  15. Evaluación auditiva neurosensorial en un grupo de prematuros del programa madre conguro Sensorineural auditory evaluation in a group of preterm neonates from the "Kangaroo mother" program

    Directory of Open Access Journals (Sweden)

    Gabriel Hernández

    1997-01-01

    Full Text Available Entre agosto de 1989 y diciembre de 1991 se buscó asociación entre algunos factores de riesgo comunes a los prematuros con peso menor de 1.500 g al nacer y el hecho de presentar disminución de la agudeza auditiva, medida con los potenciales evocados del tallo cerebral a los 4 meses y luego entre los 8 y los 14 meses. Los factores de riesgo tenidos en cuenta en 133 prematuros del ";Programa madre canguro"; del Instituto de los Seguros Sociales, en Medellín, fueron: Peso inferior a 1.500 g, hiperbilirrubinemia superior a 10 mg/ml, sufrimiento fetal, membranas hialinas, uso de aminoglicósidos, hipoglucemia, hemorragia del tercer trimestre e hipertensión arterial materna. Se halló pérdida de la agudeza auditiva en la evaluación inicial en 54 nifíos (40.6% mientras en la final sólo la presentaban 10 (7.5%; no pudo detectarse asociación entre los factores de riesgo y la disminución de la agudeza auditiva en la evaluación inicial ni en la final. La mejoría de resultados de agudeza auditiva entre las pruebas iniciales y las finales puede explicarse, entre otras razones, por la maduración cerebral del prematuro. Se debe investigar más la razón de los déficits finales y, ojalá, establecer programas de seguimiento con pruebas auditivas en este grupo de niños en riesgo. A study was carried out to investigate the association between risk factors commonly found in preterm neonates with very low birth-weight (Iess than 1.500 g and decreased auditory acuteness; the latter was measured according to brain stem evoked potentiaJs (BERA test In 133 preterm neonates belonging to the "Kangaroo mother program", in 'Medellín,Colombla. The following risk factors we~ evaluated: Hyperbilirrubinemia, hyaline membrane, birth weight lower than 1.500g, fetal distress, hypoglycemia, use of aminoglycosldes, thlrd trimester hemorrhage, and maternal high blood presssure. Abnormal results in BERA test were found in 54 cases (40.6% at 4 months and in only 10 (7

  16. Molecular Histopathology by Spectrally Reconstructed Nonlinear Interferometric Vibrational Imaging

    Science.gov (United States)

    Chowdary, Praveen D.; Jiang, Zhi; Chaney, Eric J.; Benalcazar, Wladimir A.; Marks, Daniel L.; Gruebele, Martin; Boppart, Stephen A.

    2011-01-01

    Sensitive assays for rapid quantitative analysis of histologic sections, resected tissue specimens, or in situ tissue are highly desired for early disease diagnosis. Stained histopathology is the gold standard but remains a subjective practice on processed tissue taking from hours to days. We describe a microscopy technique that obtains a sensitive and accurate color-coded image from intrinsic molecular markers. Spectrally reconstructed nonlinear interferometric vibrational imaging can differentiate cancer versus normal tissue sections with greater than 99% confidence interval in a preclinical rat breast cancer model and define cancer boundaries to ±100 μm with greater than 99% confidence interval, using fresh unstained tissue sections imaged in less than 5 minutes. By optimizing optical sources and beam delivery, this technique can potentially enable real-time point-of-care optical molecular imaging and diagnosis. PMID:21098699

  17. ACCELERATION METHODS OF NONLINEAR ITERATION FOR NONLINEAR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Guang-wei Yuan; Xu-deng Hang

    2006-01-01

    This paper discusses the accelerating iterative methods for solving the implicit scheme of nonlinear parabolic equations. Two new nonlinear iterative methods named by the implicit-explicit quasi-Newton (IEQN) method and the derivative free implicit-explicit quasi-Newton (DFIEQN) method are introduced, in which the resulting linear equations from the linearization can preserve the parabolic characteristics of the original partial differential equations. It is proved that the iterative sequence of the iteration method can converge to the solution of the implicit scheme quadratically. Moreover, compared with the Jacobian Free Newton-Krylov (JFNK) method, the DFIEQN method has some advantages, e.g., its implementation is easy, and it gives a linear algebraic system with an explicit coefficient matrix, so that the linear (inner) iteration is not restricted to the Krylov method. Computational results by the IEQN, DFIEQN, JFNK and Picard iteration meth-ods are presented in confirmation of the theory and comparison of the performance of these methods.

  18. The surface plasmon polariton dispersion relations in a nonlinear-metal-nonlinear dielectric structure of arbitrary nonlinearity

    Institute of Scientific and Technical Information of China (English)

    Liu Bing-Can; Yu Li; Lu Zhi-Xin

    2011-01-01

    The analytic surface plasmon polaritons (SPPs) dispersion relation is studied in a system consisting of a thin metallic film bounded by two sides media of nonlinear dielectric of arbitrary nonlinearity is studied by applying a generalised first integral approach. We consider both asymmetric and symmetric structures. Especially, in the symmetric system, two possible modes can exist: the odd mode and the even mode. The dispersion relations of the two modes are obtained. Due to the nonlinear dielectric, the magnitude of the electric field at the interface appears and alters the dispersion relations. The changes in SPPs dispersion relations depending on film thicknesses and nonlinearity are studied.

  19. The Dynamics of Nonlinear Inference

    Science.gov (United States)

    Kadakia, Nirag

    The determination of the hidden states of coupled nonlinear systems is frustrated by the presence of high-dimensionality, chaos, and sparse observability. This problem resides naturally in a Bayesian context: an underlying physical process produces a data stream, which - though noisy and incomplete - can in principle be inverted to express the likelihood of the underlying process itself. A large class of well-developed methods treat this problem in a sequential predict-and-correct manner that alternates information from the presumed dynamical model with information from the data. One might instead formulate this problem in a temporally global, non-sequential manner, which suggests new avenues of approach within an optimization context, but also poses new challenges in numerical implementation. The variational annealing (VA) technique is proposed to address these problems by leveraging an inherent separability between the convex and nonconvex contributions of the resulting functional forms. VA is shown to reliably track unobservable states in sparsely observed chaotic systems, as well as in minimally-observed biophysical neural models. Second, this problem can be formally cast in continuous time as a Wiener path integral, which then suggests classical solutions derived from Hamilton's principle. These solutions come with their own difficulties in that they comprise an unstable boundary-value problem. Accordingly, a further technique called Hamiltonian variational annealing is proposed, which again exploits an existing separability of convexity and nonlinearity, this time in a an enlarged manifold constrained by underlying symmetries. A running theme in this thesis is that the optimal estimate of a nonlinear system is itself a dynamical system that lives in an unstable, symplectic manifold. When this system is recast in a variational context, instability is manifested as nonconvexity, the central idea being that when this nonconvexity is incorporated in a systematic

  20. Nonlinear analysis of EAS clusters

    CERN Document Server

    Zotov, M Yu; Fomin, Y A; Fomin, Yu. A.

    2002-01-01

    We apply certain methods of nonlinear time series analysis to the extensive air shower clusters found earlier in the data set obtained with the EAS-1000 Prototype array. In particular, we use the Grassberger-Procaccia algorithm to compute the correlation dimension of samples in the vicinity of the clusters. The validity of the results is checked by surrogate data tests and some additional quantities. We compare our conclusions with the results of similar investigations performed by the EAS-TOP and LAAS groups.

  1. Modelling Loudspeaker Non-Linearities

    DEFF Research Database (Denmark)

    Agerkvist, Finn T.

    2007-01-01

    This paper investigates different techniques for modelling the non-linear parameters of the electrodynamic loudspeaker. The methods are tested not only for their accuracy within the range of original data, but also for the ability to work reasonable outside that range, and it is demonstrated...... that polynomial expansions are rather poor at this, whereas an inverse polynomial expansion or localized fitting functions such as the gaussian are better suited for modelling the Bl-factor and compliance. For the inductance the sigmoid function is shown to give very good results. Finally the time varying...

  2. Nonlinear dynamics of cell orientation

    Science.gov (United States)

    Safran, S. A.; de, Rumi

    2009-12-01

    The nonlinear dependence of cellular orientation on an external, time-varying stress field determines the distribution of orientations in the presence of noise and the characteristic time, τc , for the cell to reach its steady-state orientation. The short, local cytoskeletal relaxation time distinguishes between high-frequency (nearly perpendicular) and low-frequency (random or parallel) orientations. However, τc is determined by the much longer, orientational relaxation time. This behavior is related to experiments for which we predict the angle and characteristic time as a function of frequency.

  3. Nonlinear Optimization with Financial Applications

    CERN Document Server

    Bartholomew-Biggs, Michael

    2005-01-01

    The book introduces the key ideas behind practical nonlinear optimization. Computational finance - an increasingly popular area of mathematics degree programs - is combined here with the study of an important class of numerical techniques. The financial content of the book is designed to be relevant and interesting to specialists. However, this material - which occupies about one-third of the text - is also sufficiently accessible to allow the book to be used on optimization courses of a more general nature. The essentials of most currently popular algorithms are described, and their performan

  4. On some nonlinear potential problems

    Directory of Open Access Journals (Sweden)

    M. A. Efendiev

    1999-05-01

    Full Text Available The degree theory of mappings is applied to a two-dimensional semilinear elliptic problem with the Laplacian as principal part subject to a nonlinear boundary condition of Robin type. Under some growth conditions we obtain existence. The analysis is based on an equivalent coupled system of domain--boundary variational equations whose principal parts are the Dirichlet bilinear form in the domain and the single layer potential bilinear form on the boundary, respectively. This system consists of a monotone and a compact part. Additional monotonicity implies convergence of an appropriate Richardson iteration.

  5. Analysis of Nonlinear Directional Couplers

    Institute of Scientific and Technical Information of China (English)

    M. Liu P. Shum; N. Q. Ngo

    2003-01-01

    @@ 1 Introduction Since the coupled-mode theory in cylindrical optical-fiber systems was proposed in 1972, the optical coupling between parallel optical waveguides has been a matter of scientific concern. Two-core fiber couplers, especially, have been studied extensively since the success of producing a two-core fiber functioning as a directional coupler in 1980. The wavelength and polarization selectivity of two-core fibers can find many applications. The nonlinear properties of the two-core fiber coupler were also inspected with the realization of an ultrafast all-optical switch.

  6. Nonlinear behavior of Helmholtz resonators

    Science.gov (United States)

    Hersh, A. S.

    1990-10-01

    A semi-empirical fluid mechanical model has been derived to predict the nonlinear acoustic behavior of thin-walled, single-orifice Helmholtz resonators. The model assumed that the sound particle velocity field approaches the resonator in a spherically symmetric manner. The incident and cavity sound pressure fields are connected in terms of an orifice discharge coefficient and an end correction parameter whose values are determined empirically. The accuracy of the model was verified by comparing predicted with measured impedance over a wide range of sound amplitudes and frequencies for two different resonator geometries and with measurements conducted by Ingard and Ising.

  7. Nanoscale nonlinear PANDA ring resonator

    CERN Document Server

    Yupapin, Preecha

    2012-01-01

    Microring/nanoring resonator is an interesting device that has been widely studied and investigated by researchers from a variety of specializations. This book begins with the basic background of linear and nonlinear ring resonators. A novel design of nano device known as a PANDA ring resonator is proposed. The use of the device in the form of a PANDA in applications such as nanoelectronics, measurement, communication, sensors, optical and quantum computing, drug delivery, hybrid transistor and a new concept of electron-hole pair is discussed in detail.

  8. Nonlinear and magic ponderomotive spectroscopy

    CERN Document Server

    Moore, Kaitlin

    2015-01-01

    In ponderomotive spectroscopy an amplitude-modulated optical standing wave is employed to probe Rydberg-atom transitions, utilizing a ponderomotive rather than a dipole-field interaction. Here, we engage nonlinearities in the modulation to drive dipole-forbidden transitions up to the fifth order. We reach transition frequencies approaching the sub-THz regime. We also demonstrate magic-wavelength conditions, which result in symmetric spectral lines with a Fourier-limited feature at the line center. Applicability to precision measurement is discussed.

  9. Statistical methods in nonlinear dynamics

    Indian Academy of Sciences (India)

    K P N Murthy; R Harish; S V M Satyanarayana

    2005-03-01

    Sensitivity to initial conditions in nonlinear dynamical systems leads to exponential divergence of trajectories that are initially arbitrarily close, and hence to unpredictability. Statistical methods have been found to be helpful in extracting useful information about such systems. In this paper, we review briefly some statistical methods employed in the study of deterministic and stochastic dynamical systems. These include power spectral analysis and aliasing, extreme value statistics and order statistics, recurrence time statistics, the characterization of intermittency in the Sinai disorder problem, random walk analysis of diffusion in the chaotic pendulum, and long-range correlations in stochastic sequences of symbols.

  10. Strong nonlinear focusing of light in nonlinearly controlled electromagnetic active metamaterial field concentrators

    Science.gov (United States)

    Rapoport, Yu G.; Boardman, A. D.; Grimalsky, V. V.; Ivchenko, V. M.; Kalinich, N.

    2014-05-01

    The idea of nonlinear ‘transformation optics-inspired’ [1-6] electromagnetic cylindrical field concentrators has been taken up in a preliminary manner in a number of conference reports [7-9]. Such a concentrator includes both external linear region with a dielectric constant increased towards the centre and internal region with nonlinearity characterized by constant coefficients. Then, in the process of farther investigations we realized the following factors considered neither in [7-9] nor in the recent paper [10]: saturation of nonlinearity, nonlinear losses, linear gain, numerical convergence, when nonlinear effect becomes very strong and formation of ‘hotspots’ starts. It is clearly demonstrated here that such a strongly nonlinear process starts when the nonlinear amplitude of any incident beam(s) exceeds some ‘threshold’ value. Moreover, it is shown that the formation of hotspots may start as the result of any of the following processes: an increase of the input amplitude, increasing the linear amplification in the central nonlinear region, decreasing the nonlinear losses, a decrease in the saturation of the nonlinearity. Therefore, a tendency to a formation of ‘hotspots’ is a rather universal feature of the strongly nonlinear behaviour of the ‘nonlinear resonator’ system, while at the same time the system is not sensitive to the ‘prehistory’ of approaching nonlinear threshold intensity (amplitude). The new proposed method includes a full-wave nonlinear solution analysis (in the nonlinear region), a new form of complex geometric optics (in the linear inhomogeneous external cylinder), and new boundary conditions, matching both solutions. The observed nonlinear phenomena will have a positive impact upon socially and environmentally important devices of the future. Although a graded-index concentrator is used here, it is a direct outcome of transformation optics. Numerical evaluations show that for known materials these nonlinear effects

  11. The quantum theory of nonlinear optics

    CERN Document Server

    Drummond, Peter D

    2014-01-01

    Playing a prominent role in communications, quantum science and laser physics, quantum nonlinear optics is an increasingly important field. This book presents a self-contained treatment of field quantization and covers topics such as the canonical formalism for fields, phase-space representations and the encompassing problem of quantization of electrodynamics in linear and nonlinear media. Starting with a summary of classical nonlinear optics, it then explains in detail the calculation techniques for quantum nonlinear optical systems and their applications, quantum and classical noise sources in optical fibers and applications of nonlinear optics to quantum information science. Supplemented by end-of-chapter exercises and detailed examples of calculation techniques in different systems, this book is a valuable resource for graduate students and researchers in nonlinear optics, condensed matter physics, quantum information and atomic physics. A solid foundation in quantum mechanics and classical electrodynamic...

  12. Nonlinear optical crystals a complete survey

    CERN Document Server

    Nikogosyan, David N

    2005-01-01

    Nonlinear optical crystals are widely used in modern optical science and technology for frequency conversion of laser light, i.e. to generate laser radiation at any specific wavelength in visible, UV or IR spectral regions. This unrivalled reference book contains the most complete and up-to-date information on properties of nonlinear optical crystals. It includes: * Database of 63 common and novel nonlinear optical crystals * Periodically-poled and self-frequency-doubling materials * Full description of linear and nonlinear optical properties * Significant amount of crystallophysical, thermophysical, spectroscopic, electro-optic and magneto-optic information * 7 mini-reviews on novel applications, such as deep-UV light generation, terahertz-wave generation, ultrashort laser pulse compression, photonic band-gap crystals, x3 nonlinearity, etc. * More than 1500 different references with full titles It is a vital source of information for scientists and engineers dealing with modern applications of nonlinear opti...

  13. Mathematical modeling and applications in nonlinear dynamics

    CERN Document Server

    Merdan, Hüseyin

    2016-01-01

    The book covers nonlinear physical problems and mathematical modeling, including molecular biology, genetics, neurosciences, artificial intelligence with classical problems in mechanics and astronomy and physics. The chapters present nonlinear mathematical modeling in life science and physics through nonlinear differential equations, nonlinear discrete equations and hybrid equations. Such modeling can be effectively applied to the wide spectrum of nonlinear physical problems, including the KAM (Kolmogorov-Arnold-Moser (KAM)) theory, singular differential equations, impulsive dichotomous linear systems, analytical bifurcation trees of periodic motions, and almost or pseudo- almost periodic solutions in nonlinear dynamical systems. Provides methods for mathematical models with switching, thresholds, and impulses, each of particular importance for discontinuous processes Includes qualitative analysis of behaviors on Tumor-Immune Systems and methods of analysis for DNA, neural networks and epidemiology Introduces...

  14. Nonlinear magnetohydrodynamics of edge localized mode precursors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. B., E-mail: guozhipku@gmail.com [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China); WCI Center for Fusion Theory, NFRI, Gwahangno 113, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Wang, Lu [SEEE, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang, X. G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China)

    2015-02-15

    A possible origin of edge-localized-mode (ELM) precursors based on nonlinear ideal peeling-ballooning mode is reported. Via nonlinear variational principle, a nonlinear evolution equation of the radial displacement is derived and solved, analytically. Besides an explosive growth in the initial nonlinear phase, it is found that the local displacement evolves into an oscillating state in the developed nonlinear phase. The nonlinear frequency of the ELM precursors scales as ω{sub pre}∼x{sup 1/3}ξ{sup ^}{sub ψ,in}{sup 2/3}n, with x position in radial direction, ξ{sup ^}{sub ψ,in} strength of initial perturbation, and n toroidal mode number.

  15. Nonlinear parallel momentum transport in strong turbulence

    CERN Document Server

    Wang, Lu; Diamond, P H

    2015-01-01

    Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the \\emph{nonlinear} momentum flux-$$. However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas {\\bf 18}, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong turbulence is calculated by using three dimensional Hasegawa-Mima equation. It is shown that nonlinear diffusivity is smaller than quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so could be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.

  16. Nonlinear optical properties of ultrathin metal layers

    DEFF Research Database (Denmark)

    Lysenko, Oleg

    2016-01-01

    . The optical characterization of the plasmonic waveguides is performed using femtosecond and picosecond optical pulses. Two nonlinear optical effects in the strip plasmonic waveguides are experimentally observed and reported. The first effect is the nonlinear power transmission of the plasmonic mode......-order nonlinear susceptibility of the plasmonic mode in the gold strip waveguides significantly depends on the metal layer thickness and laser pulse duration. This dependence is explained in detail in terms of the free-electron temporal dynamics in gold. The third-order nonlinear susceptibility of the gold layer...... duration dependence of the third-order nonlinear susceptibility of gold is calculated in the broad range from tens of femtoseconds to tens of picoseconds using the two-temperature model of the free-electron temporal dynamics of gold, and shows the saturation of the thirdorder nonlinear susceptibility...

  17. Nonlinear Effects in the Cosmic Microwave Background

    CERN Document Server

    Maartens, R

    2000-01-01

    Major advances in the observation and theory of cosmic microwave background anisotropies have opened up a new era in cosmology. This has encouraged the hope that the fundamental parameters of cosmology will be determined to high accuracy in the near future. However, this optimism should not obscure the ongoing need for theoretical developments that go beyond the highly successful but simplified standard model. Such developments include improvements in observational modelling (e.g. foregrounds, non-Gaussian features), extensions and alternatives to the simplest inflationary paradigm (e.g. non-adiabatic effects, defects), and investigation of nonlinear effects. In addition to well known nonlinear effects such as the Rees-Sciama and Ostriker-Vishniac effects, further nonlinear effects have recently been identified. These include a Rees-Sciama-type tensor effect, time-delay effects of scalar and tensor lensing, nonlinear Thomson scattering effects and a nonlinear shear effect. Some of the nonlinear effects and th...

  18. A nonlinear plate control without linearization

    Directory of Open Access Journals (Sweden)

    Yildirim Kenan

    2017-03-01

    Full Text Available In this paper, an optimal vibration control problem for a nonlinear plate is considered. In order to obtain the optimal control function, wellposedness and controllability of the nonlinear system is investigated. The performance index functional of the system, to be minimized by minimum level of control, is chosen as the sum of the quadratic 10 functional of the displacement. The velocity of the plate and quadratic functional of the control function is added to the performance index functional as a penalty term. By using a maximum principle, the nonlinear control problem is transformed to solving a system of partial differential equations including state and adjoint variables linked by initial-boundary-terminal conditions. Hence, it is shown that optimal control of the nonlinear systems can be obtained without linearization of the nonlinear term and optimal control function can be obtained analytically for nonlinear systems without linearization.

  19. The road towards nonlinear magneto-plasmonics

    Science.gov (United States)

    Zheng, Wei; Liu, Xiao; Lüpke, Günter; Hanbicki, Aubrey T.; Jonker, Berend T.

    2016-10-01

    Nonlinear magneto-plasmonics (NMP) describes systems where nonlinear optics, magnetics and plasmonics are all involved. NMP can be referred to as interdisciplinary studies at the intersection of Nonlinear Plasmonics (NP), Magneto- Plasmonics (MP), and nanoscience. In NMP systems, nanostructures are the bases, Surface Plasmons (SPs) work as catalyst due to strong field enhancement effects, and the nonlinear magneto-optical Kerr effect (nonlinear MOKE) plays an important role as a characterization method. Many new effects were discovered recently, which include enhanced magnetization-induced harmonic generation, controlled and enhanced magnetic contrast, magneto-chiral effect, correlation between giant magnetroresistance (GMR) and nonlinear MOKE, etc. We review the structures, experiments, findings, and the applications of NMP.

  20. Introduction to nonlinear finite element analysis

    CERN Document Server

    Kim, Nam-Ho

    2015-01-01

    This book introduces the key concepts of nonlinear finite element analysis procedures. The book explains the fundamental theories of the field and provides instructions on how to apply the concepts to solving practical engineering problems. Instead of covering many nonlinear problems, the book focuses on three representative problems: nonlinear elasticity, elastoplasticity, and contact problems. The book is written independent of any particular software, but tutorials and examples using four commercial programs are included as appendices: ANSYS, NASTRAN, ABAQUS, and MATLAB. In particular, the MATLAB program includes all source codes so that students can develop their own material models, or different algorithms. This book also: ·         Presents clear explanations of nonlinear finite element analysis for elasticity, elastoplasticity, and contact problems ·         Includes many informative examples of nonlinear analyses so that students can clearly understand the nonlinear theory ·    ...